diff --git a/config/routes.rb b/config/routes.rb
index f5e255e810cd50842a4a83d27c9c77a75226f449..5b6105b6527a1e5e92c41a3d66961f046e019a5b 100644
--- a/config/routes.rb
+++ b/config/routes.rb
@@ -62,7 +62,7 @@
     scope path: '/users/sign_up', module: :registrations, as: :users_sign_up do
       Gitlab.ee do
         resource :welcome, only: [:show, :update], controller: 'welcome'
-        resource :trial_welcome, only: [:new], controller: 'trial_welcome'
+        resource :trial_welcome, only: [:new, :create], controller: 'trial_welcome'
         resource :company, only: [:new, :create], controller: 'company'
         resources :groups, only: [:new, :create]
       end
diff --git a/ee/app/assets/javascripts/trials/components/create_trial_welcome_form.vue b/ee/app/assets/javascripts/trials/components/create_trial_welcome_form.vue
index 9777744f409387df60973c587fde0be3e3795127..0a37df5dcf08456a76be95afb8bf1dbc324214dd 100644
--- a/ee/app/assets/javascripts/trials/components/create_trial_welcome_form.vue
+++ b/ee/app/assets/javascripts/trials/components/create_trial_welcome_form.vue
@@ -58,20 +58,22 @@ export default {
       type: String,
       required: true,
     },
+    namespaceId: {
+      type: Number,
+      required: false,
+      default: null,
+    },
+    serverValidations: {
+      type: Object,
+      required: false,
+      default: () => ({}),
+    },
   },
   data() {
     return {
-      formValues: {
-        first_name: this.userData.firstName,
-        last_name: this.userData.lastName,
-        company_name: this.userData.companyName,
-        country: this.userData.country,
-        state: this.userData.state,
-        group_name: '',
-        project_name: '',
-      },
       countries: [],
       states: [],
+      formValues: {},
     };
   },
   computed: {
@@ -162,17 +164,19 @@ export default {
         }
       }
 
+      let groupNameValidators = [];
+      if (this.namespaceId === null)
+        groupNameValidators = [formValidators.required(__('Group name is required.'))];
+
       result.group_name = {
         label: ' ',
         groupAttrs: {
           class: 'gl-col-span-12',
         },
         inputAttrs: {
-          name: 'group_name',
-          'data-testid': 'group-name-input',
-          placeholder: __('You use groups to organize your projects'),
+          disabled: this.namespaceId !== null,
         },
-        validators: [formValidators.required(__('Group name is required.'))],
+        validators: groupNameValidators,
       };
 
       result.project_name = {
@@ -180,14 +184,15 @@ export default {
         groupAttrs: {
           class: 'gl-col-span-12',
         },
-        inputAttrs: {
-          name: 'project_name',
-          'data-testid': 'project-name-input',
-          placeholder: __('Projects contain the resources for your repository'),
-        },
         validators: [formValidators.required(__('Project name is required.'))],
       };
 
+      result.namespace_id = {
+        groupAttrs: {
+          class: 'gl-hidden',
+        },
+      };
+
       return result;
     },
   },
@@ -196,6 +201,18 @@ export default {
       this.resetSelectedState();
     },
   },
+  mounted() {
+    this.formValues = {
+      first_name: this.userData.firstName,
+      last_name: this.userData.lastName,
+      company_name: this.userData.companyName,
+      country: this.userData.country,
+      state: this.userData.state,
+      group_name: this.userData.groupName || '',
+      project_name: this.userData.projectName || '',
+      namespace_id: this.namespaceId,
+    };
+  },
   methods: {
     onSubmit() {
       trackSaasTrialLeadSubmit(this.gtmSubmitEventLabel, this.userData.emailDomain);
@@ -266,6 +283,7 @@ export default {
       :form-id="$options.formId"
       :fields="fields"
       class="gl-grid md:gl-gap-x-4"
+      :server-validations="serverValidations"
       @submit="onSubmit"
     >
       <template #input(country)>
@@ -291,7 +309,8 @@ export default {
           data-testid="state-dropdown"
         />
       </template>
-      <template #input(group_name)="{ id, value }">
+
+      <template #input(group_name)="{ id, value, input = () => {}, blur = () => {} }">
         <div class="gl-flex">
           <gl-form-group
             class="gl-mb-0 gl-flex-grow"
@@ -299,7 +318,14 @@ export default {
             :label="__('Group Name')"
             data-testid="group-name-group"
           >
-            <gl-form-input :id="id" />
+            <gl-form-input
+              :id="id"
+              name="group_name"
+              :value="value"
+              :disabled="fields.group_name.inputAttrs.disabled"
+              @input="input"
+              @blur="blur"
+            />
           </gl-form-group>
           <div
             class="gl-z-1 gl-ml-6 gl-mt-2 gl-flex gl-w-11 gl-items-center gl-justify-center gl-rounded-lg gl-bg-gray-50 gl-px-8 gl-text-size-h1-xl gl-font-semibold"
@@ -310,7 +336,7 @@ export default {
         </div>
       </template>
 
-      <template #input(project_name)="{ id }">
+      <template #input(project_name)="{ id, value, input = () => {}, blur = () => {} }">
         <div class="gl-flex">
           <gl-form-group
             class="gl-mb-0 gl-flex-grow"
@@ -318,7 +344,13 @@ export default {
             :label="__('Project Name')"
             data-testid="project-name-group"
           >
-            <gl-form-input :id="id" />
+            <gl-form-input
+              :id="id"
+              name="project_name"
+              :value="value"
+              @input="input"
+              @blur="blur"
+            />
           </gl-form-group>
           <div class="gl-relative gl-ml-8 gl-w-11">
             <div
@@ -327,6 +359,10 @@ export default {
           </div>
         </div>
       </template>
+
+      <template #input(namespace_id)="{ value }">
+        <input type="hidden" :value="value" name="namespace_id" />
+      </template>
     </gl-form-fields>
 
     <gl-button
diff --git a/ee/app/components/gitlab_subscriptions/trials/welcome/trial_form_component.rb b/ee/app/components/gitlab_subscriptions/trials/welcome/trial_form_component.rb
index 15b7bb91dba98fc0d2aef3056f3379e7335c269e..2bbb872fe7e7be49ff27cc15a54cb48266b907f6 100644
--- a/ee/app/components/gitlab_subscriptions/trials/welcome/trial_form_component.rb
+++ b/ee/app/components/gitlab_subscriptions/trials/welcome/trial_form_component.rb
@@ -18,28 +18,28 @@ def form_data
             {
               userData: user_data,
               submitPath: submit_path,
-              gtmSubmitEventLabel: 'saasTrialSubmit'
+              gtmSubmitEventLabel: 'saasTrialSubmit',
+              namespaceId: params[:namespace_id],
+              serverValidations: params[:errors] || {}
             }
           )
         end
 
         def user_data
           {
-            firstName: user.first_name,
-            lastName: user.last_name,
+            firstName: params[:first_name] || user.first_name,
+            lastName: params[:last_name] || user.last_name,
             emailDomain: user.email_domain,
-            companyName: user.user_detail_organization,
-            country: '',
-            state: ''
+            companyName: params[:company_name] || user.user_detail_organization,
+            country: params[:country] || '',
+            state: params[:state] || '',
+            groupName: params[:group_name] || '',
+            projectName: params[:project_name] || ''
           }
         end
 
         def submit_path
-          # placeholder route
-          trials_path(
-            step: GitlabSubscriptions::Trials::UltimateCreateService::FULL,
-            **params.slice(*::Onboarding::StatusPresenter::GLM_PARAMS)
-          )
+          users_sign_up_trial_welcome_path(**params.slice(*::Onboarding::StatusPresenter::GLM_PARAMS))
         end
       end
     end
diff --git a/ee/app/controllers/registrations/trial_welcome_controller.rb b/ee/app/controllers/registrations/trial_welcome_controller.rb
index 83cc040cb08685e1710fdb59604ddb0e85e098c7..dcd905ce69bef5b49347d86c61fe6de9b224061a 100644
--- a/ee/app/controllers/registrations/trial_welcome_controller.rb
+++ b/ee/app/controllers/registrations/trial_welcome_controller.rb
@@ -20,10 +20,46 @@ def new
         params: params.permit(*::Onboarding::StatusPresenter::GLM_PARAMS))
     end
 
+    def create
+      result = GitlabSubscriptions::Trials::WelcomeCreateService.new(params: create_params,
+        user: current_user, **progress_params).execute
+
+      if result.success?
+        redirect_to namespace_project_learn_gitlab_path(result.payload[:namespace_id], result.payload[:project_id])
+      elsif result.reason == GitlabSubscriptions::Trials::UltimateCreateService::NOT_FOUND
+        render_404
+      elsif result.payload[:model_errors].present?
+        render GitlabSubscriptions::Trials::Welcome::TrialFormComponent.new(user: current_user,
+          params: resubmit_params(result))
+      end
+    end
+
     private
 
     def enable_dark_mode
       @html_class = 'gl-dark'
     end
+
+    def glm_params
+      params.permit(*::Onboarding::StatusPresenter::GLM_PARAMS)
+    end
+
+    def resubmit_params(result)
+      { namespace_id: result.payload[:namespace_id],
+        errors: result.payload[:model_errors] }.merge(create_params).to_h.symbolize_keys
+    end
+
+    def create_params
+      params.permit(
+        *::Onboarding::StatusPresenter::GLM_PARAMS,
+        :group_name, :project_name, :company_name, :first_name, :last_name, :country, :state
+      ).with_defaults(organization_id: Current.organization.id)
+    end
+
+    def progress_params
+      progress = params.permit(:namespace_id, :project_id, :lead_created)
+      progress[:lead_created] = !!ActiveModel::Type::Boolean.new.cast(progress[:lead_created])
+      progress.to_h.symbolize_keys
+    end
   end
 end
diff --git a/ee/app/services/gitlab_subscriptions/trials/welcome_create_service.rb b/ee/app/services/gitlab_subscriptions/trials/welcome_create_service.rb
index f325390fa05819f0961f37fa85abf2a4e9d6b8e1..386a340bff89ad4929d89f10b0fb37881da88872 100644
--- a/ee/app/services/gitlab_subscriptions/trials/welcome_create_service.rb
+++ b/ee/app/services/gitlab_subscriptions/trials/welcome_create_service.rb
@@ -45,7 +45,7 @@ def execute
       attr_reader :user, :params, :namespace, :project, :namespace_id, :project_id, :lead_created
 
       def create_group
-        name = ActionController::Base.helpers.sanitize(params[:group_name])
+        name = ActionController::Base.helpers.sanitize(params[:group_name], tags: [])
         group_params = {
           name: name,
           path: Namespace.clean_path(name.parameterize),
@@ -63,7 +63,7 @@ def create_group
 
       def create_project
         project_params = {
-          name: ActionController::Base.helpers.sanitize(params[:project_name]),
+          name: ActionController::Base.helpers.sanitize(params[:project_name], tags: []),
           namespace_id: namespace.id,
           organization_id: namespace.organization_id
         }
@@ -101,7 +101,7 @@ def trial_params
         }
 
         params.slice(*::Onboarding::StatusPresenter::GLM_PARAMS, :namespace_id)
-              .merge(gl_com_params, namespace_params).to_h.symbolize_keys
+          .merge(gl_com_params, namespace_params).to_h.symbolize_keys
       end
 
       def lead_params
@@ -122,8 +122,8 @@ def lead_params
 
       def model_errors
         {
-          group: namespace.try(:errors).try(:full_messages),
-          project: project.try(:errors).try(:full_messages)
+          group_name: namespace.try(:errors).try(:full_messages).try(:to_sentence),
+          project_name: project.try(:errors).try(:full_messages).try(:to_sentence)
         }.select { |_m, e| e.present? }
       end
 
diff --git a/ee/spec/components/gitlab_subscriptions/trials/welcome/trial_form_component_spec.rb b/ee/spec/components/gitlab_subscriptions/trials/welcome/trial_form_component_spec.rb
index 0049fea96a7e8b59f79aef5a1ddf893b15144ff3..5614c5ee13ef660ff15aa37445714de5863d0165 100644
--- a/ee/spec/components/gitlab_subscriptions/trials/welcome/trial_form_component_spec.rb
+++ b/ee/spec/components/gitlab_subscriptions/trials/welcome/trial_form_component_spec.rb
@@ -3,8 +3,268 @@
 require 'spec_helper'
 
 RSpec.describe GitlabSubscriptions::Trials::Welcome::TrialFormComponent, :aggregate_failures, type: :component, feature_category: :acquisition do
-  it_behaves_like described_class do
-    let(:additional_kwargs) { {} }
-    let(:extra_namespace_data) { {} }
+  let(:user) { build(:user, first_name: 'John', last_name: 'Doe', user_detail_organization: 'Acme Corp') }
+  let(:form_params) do
+    {
+      glm_source: 'some-source',
+      glm_content: 'some-content'
+    }.with_indifferent_access
+  end
+
+  let(:kwargs) do
+    { user: user, params: form_params }
+  end
+
+  subject(:component) { render_inline(described_class.new(**kwargs)) && page }
+
+  context 'with default content' do
+    let(:expected_form_data_attributes) do
+      {
+        userData: {
+          firstName: user.first_name,
+          lastName: user.last_name,
+          emailDomain: user.email_domain,
+          companyName: user.user_detail_organization,
+          groupName: '',
+          projectName: '',
+          country: '',
+          state: ''
+        },
+        submitPath: users_sign_up_trial_welcome_path(glm_source: 'some-source', glm_content: 'some-content'),
+        gtmSubmitEventLabel: 'saasTrialSubmit'
+      }.with_indifferent_access
+    end
+
+    it { is_expected.to have_content('Welcome to GitLab') }
+
+    it 'has body content' do
+      is_expected
+        .to have_content('We need a few more details from you to activate your trial.')
+    end
+
+    it 'renders form with correct attributes' do
+      expect_form_data_attribute(expected_form_data_attributes)
+    end
+
+    it 'includes all user data fields' do
+      view_model = parsed_view_model
+      user_data = view_model['userData']
+
+      expect(user_data['firstName']).to eq(user.first_name)
+      expect(user_data['lastName']).to eq(user.last_name)
+      expect(user_data['emailDomain']).to eq(user.email_domain)
+      expect(user_data['companyName']).to eq(user.user_detail_organization)
+      expect(user_data['groupName']).to eq('')
+      expect(user_data['projectName']).to eq('')
+      expect(user_data['country']).to eq('')
+      expect(user_data['state']).to eq('')
+    end
+
+    it 'includes submit path with all parameters' do
+      view_model = parsed_view_model
+      expected_path = users_sign_up_trial_welcome_path(glm_source: 'some-source', glm_content: 'some-content')
+
+      expect(view_model['submitPath']).to eq(expected_path)
+    end
+
+    it 'includes GTM event label' do
+      view_model = parsed_view_model
+      expect(view_model['gtmSubmitEventLabel']).to eq('saasTrialSubmit')
+    end
+  end
+
+  context 'when glm_params are not provided' do
+    let(:form_params) { {}.with_indifferent_access }
+    let(:expected_form_data_attributes) do
+      {
+        userData: {
+          firstName: user.first_name,
+          lastName: user.last_name,
+          emailDomain: user.email_domain,
+          companyName: user.user_detail_organization,
+          groupName: '',
+          projectName: '',
+          country: '',
+          state: ''
+        },
+        submitPath: users_sign_up_trial_welcome_path,
+        gtmSubmitEventLabel: 'saasTrialSubmit'
+      }.with_indifferent_access
+    end
+
+    it 'renders form with correct attributes' do
+      expect_form_data_attribute(expected_form_data_attributes)
+    end
+
+    it 'excludes GLM params from submit path' do
+      view_model = parsed_view_model
+      submit_path = view_model['submitPath']
+
+      expect(submit_path).not_to include('glm_source')
+      expect(submit_path).not_to include('glm_content')
+    end
+  end
+
+  describe 'user data variations' do
+    context 'when user has blank last name' do
+      let(:user) { build(:user, first_name: 'John', last_name: '', user_detail_organization: 'Acme Corp') }
+      let(:expected_form_data_attributes) do
+        {
+          userData: {
+            firstName: user.first_name,
+            lastName: user.last_name,
+            emailDomain: user.email_domain,
+            companyName: user.user_detail_organization,
+            groupName: '',
+            projectName: '',
+            country: '',
+            state: ''
+          }
+        }.with_indifferent_access
+      end
+
+      it 'renders form with correct attributes' do
+        expect_form_data_attribute(expected_form_data_attributes)
+      end
+    end
+
+    context 'when user has present last name' do
+      let(:user) { build(:user, first_name: 'John', last_name: 'Doe', user_detail_organization: 'Acme Corp') }
+
+      it 'includes last name in user data' do
+        view_model = parsed_view_model
+        user_data = view_model['userData']
+
+        expect(user_data['lastName']).to eq('Doe')
+      end
+    end
+
+    context 'when user has no organization' do
+      let(:user) { build(:user, first_name: 'John', last_name: 'Doe', user_detail_organization: nil) }
+
+      it 'handles nil organization gracefully' do
+        view_model = parsed_view_model
+        expect(view_model.dig('userData', 'companyName')).to be_nil
+      end
+    end
+
+    context 'when user has blank organization' do
+      let(:user) { build(:user, first_name: 'John', last_name: 'Doe', user_detail_organization: '') }
+
+      it 'handles blank organization' do
+        view_model = parsed_view_model
+        expect(view_model.dig('userData', 'companyName')).to eq('')
+      end
+    end
+
+    context 'when user has special characters in name' do
+      let(:user) { build(:user, first_name: "John's", last_name: 'O\'Connor', user_detail_organization: 'Acme & Co.') }
+
+      it 'handles special characters in user data' do
+        view_model = parsed_view_model
+        user_data = view_model['userData']
+
+        expect(user_data['firstName']).to eq("John's")
+        expect(user_data['lastName']).to eq('O\'Connor')
+        expect(user_data['companyName']).to eq('Acme & Co.')
+      end
+    end
+  end
+
+  describe 'form data structure' do
+    it 'generates valid JSON' do
+      view_model = parsed_view_model
+      expect(view_model).to be_a(Hash)
+    end
+
+    it 'includes all required top-level keys' do
+      view_model = parsed_view_model
+
+      expect(view_model).to have_key('userData')
+      expect(view_model).to have_key('submitPath')
+      expect(view_model).to have_key('gtmSubmitEventLabel')
+    end
+
+    it 'has userData as a hash' do
+      view_model = parsed_view_model
+      expect(view_model['userData']).to be_a(Hash)
+    end
+
+    it 'has submitPath as a string' do
+      view_model = parsed_view_model
+      expect(view_model['submitPath']).to be_a(String)
+    end
+
+    it 'has gtmSubmitEventLabel as a string' do
+      view_model = parsed_view_model
+      expect(view_model['gtmSubmitEventLabel']).to be_a(String)
+    end
+
+    it 'includes all required userData fields' do
+      view_model = parsed_view_model
+      user_data = view_model['userData']
+
+      expected_keys = %w[firstName lastName emailDomain companyName groupName projectName country state]
+      expect(user_data.keys).to match_array(expected_keys)
+    end
+  end
+
+  describe 'parameter handling edge cases' do
+    context 'with only glm_source provided' do
+      let(:form_params) { { glm_source: 'partial-source' }.with_indifferent_access }
+
+      it 'includes partial GLM params in submit path' do
+        view_model = parsed_view_model
+        submit_path = view_model['submitPath']
+
+        expect(submit_path).to include('glm_source=partial-source')
+        expect(submit_path).not_to include('glm_content')
+      end
+    end
+
+    context 'with only glm_content provided' do
+      let(:form_params) { { glm_content: 'partial-content' }.with_indifferent_access }
+
+      it 'includes partial GLM params in submit path' do
+        view_model = parsed_view_model
+        submit_path = view_model['submitPath']
+
+        expect(submit_path).to include('glm_content=partial-content')
+        expect(submit_path).not_to include('glm_source')
+      end
+    end
+
+    context 'with additional unrecognized params' do
+      let(:form_params) do
+        {
+          glm_source: 'some-source',
+          glm_content: 'some-content',
+          random_param: 'should-be-ignored'
+        }.with_indifferent_access
+      end
+
+      it 'only includes recognized params in submit path' do
+        view_model = parsed_view_model
+        submit_path = view_model['submitPath']
+
+        expect(submit_path).to include('glm_source=some-source')
+        expect(submit_path).to include('glm_content=some-content')
+        expect(submit_path).not_to include('random_param')
+      end
+    end
+  end
+
+  def parsed_view_model
+    actual_element = component.find('#js-create-trial-welcome-form')
+    data_view_model = actual_element['data-view-model']
+    ::Gitlab::Json.parse(data_view_model)
+  end
+
+  def expect_form_data_attribute(data_attributes)
+    view_model = parsed_view_model
+
+    data_attributes.each do |attribute, value|
+      expect(view_model[attribute]).to eq(value)
+    end
   end
 end
diff --git a/ee/spec/frontend/trials/components/create_trial_welcome_form_spec.js b/ee/spec/frontend/trials/components/create_trial_welcome_form_spec.js
index 828e4d8741e4687951b7fd5158cc33d8a8632ac7..87da8e114332f10603775d3e81aad7ab03129690 100644
--- a/ee/spec/frontend/trials/components/create_trial_welcome_form_spec.js
+++ b/ee/spec/frontend/trials/components/create_trial_welcome_form_spec.js
@@ -31,6 +31,9 @@ describe('CreateTrialWelcomeForm', () => {
     country: 'US',
     state: 'NY',
     emailDomain: 'example.com',
+    namespaceId: null,
+    groupName: '',
+    projectName: '',
   };
 
   const createComponent = async ({
@@ -38,6 +41,8 @@ describe('CreateTrialWelcomeForm', () => {
     propsData = {},
     countriesLoading = false,
     statesLoading = false,
+    serverValidations = {},
+    namespaceId,
     data,
   } = {}) => {
     const mockResolvers = {
@@ -63,6 +68,8 @@ describe('CreateTrialWelcomeForm', () => {
         userData,
         submitPath,
         gtmSubmitEventLabel,
+        serverValidations,
+        namespaceId,
         ...propsData,
       },
       stubs: {
@@ -96,8 +103,9 @@ describe('CreateTrialWelcomeForm', () => {
           company_name: defaultUserData.companyName,
           country: defaultUserData.country,
           state: defaultUserData.state,
-          group_name: '',
-          project_name: '',
+          group_name: defaultUserData.groupName,
+          project_name: defaultUserData.projectName,
+          namespace_id: defaultUserData.namespaceId,
         });
       });
 
@@ -114,6 +122,7 @@ describe('CreateTrialWelcomeForm', () => {
           company_name: undefined, // userData.companyName is undefined
           country: undefined, // userData.country is undefined
           state: undefined, // userData.state is undefined
+          namespace_id: null,
           group_name: '',
           project_name: '',
         });
@@ -153,8 +162,6 @@ describe('CreateTrialWelcomeForm', () => {
           { key: 'company_name', name: 'company_name' },
           { key: 'country', name: undefined },
           { key: 'state', name: undefined },
-          { key: 'group_name', name: 'group_name' },
-          { key: 'project_name', name: 'project_name' },
         ];
 
         expectedFields.forEach(({ key, name }) => {
@@ -173,8 +180,9 @@ describe('CreateTrialWelcomeForm', () => {
           company_name: defaultUserData.companyName,
           country: defaultUserData.country,
           state: defaultUserData.state,
-          group_name: '',
-          project_name: '',
+          group_name: defaultUserData.groupName,
+          project_name: defaultUserData.projectName,
+          namespace_id: null,
         };
         expect(formValues()).toEqual(initialValues);
 
@@ -397,5 +405,31 @@ describe('CreateTrialWelcomeForm', () => {
       );
       expect(submitSpy).toHaveBeenCalled();
     });
+
+    describe('namespace create errors', () => {
+      it('passes namespace create errors to GlFormFields when createErrors exist', async () => {
+        const serverValidations = { group_name: ['Error msg'] };
+        wrapper = await createComponent({ serverValidations });
+
+        expect(findFormFields().props('serverValidations')).toEqual(serverValidations);
+      });
+
+      it('passes empty server validations to GlFormFields when valid', async () => {
+        const serverValidations = {};
+        wrapper = await createComponent({ serverValidations });
+
+        expect(findFormFields().props('serverValidations')).toEqual(serverValidations);
+      });
+    });
+
+    describe('with hidden namespace_id field', () => {
+      it('value is rendered in hidden input and group name input is disabled', async () => {
+        wrapper = await createComponent({ namespaceId: 1234 });
+
+        expect(fieldsProps().group_name.validators).toHaveLength(0);
+        expect(fieldsProps()).toHaveProperty('namespace_id');
+        expect(fieldsProps().group_name.inputAttrs.disabled).toBe(true);
+      });
+    });
   });
 });
diff --git a/ee/spec/requests/registrations/trial_welcome_controller_spec.rb b/ee/spec/requests/registrations/trial_welcome_controller_spec.rb
index 5ed9d4c2a7ee31d3a5d0169d0c148ec3909e33be..2f9ab4af1affa6c62538cd83610dee6b44df5dba 100644
--- a/ee/spec/requests/registrations/trial_welcome_controller_spec.rb
+++ b/ee/spec/requests/registrations/trial_welcome_controller_spec.rb
@@ -2,10 +2,17 @@
 
 require 'spec_helper'
 
-RSpec.describe Registrations::TrialWelcomeController, :saas, feature_category: :onboarding do
-  let_it_be(:user) { create(:user) }
+RSpec.describe Registrations::TrialWelcomeController, :with_current_organization, :saas, feature_category: :onboarding do
+  let_it_be(:user, reload: true) { create(:user, organizations: [current_organization]) }
+  let_it_be(:add_on_purchase) { build(:gitlab_subscription_add_on_purchase) }
   let(:glm_params) { { glm_source: '_glm_source_', glm_content: '_glm_content_' } }
 
+  let(:subscriptions_trials_enabled) { true }
+
+  before do
+    stub_saas_features(subscriptions_trials: subscriptions_trials_enabled, marketing_google_tag_manager: false)
+  end
+
   describe 'GET #new' do
     let(:base_params) { glm_params }
 
@@ -49,4 +56,125 @@
       end
     end
   end
+
+  describe 'POST create' do
+    let_it_be(:group_for_trial, reload: true) { create(:group_with_plan, plan: :free_plan, owners: user) }
+    let(:default_params) do
+      {
+        first_name: '_first_name_',
+        last_name: '_last_name_',
+        company_name: '_company_name_',
+        country: '_country_',
+        state: '_state_',
+        group_name: "group name",
+        project_name: "project name",
+        organization_id: current_organization.id
+      }.merge(glm_params).with_indifferent_access
+    end
+
+    let(:params) { default_params }
+    let(:namespace_id) { 1 }
+    let(:project_id) { 1 }
+
+    subject(:post_create) do
+      post users_sign_up_trial_welcome_path, params: params
+      response
+    end
+
+    context 'when authenticated', :use_clean_rails_memory_store_caching do
+      before do
+        login_as(user)
+      end
+
+      it "when successful" do
+        expect(GitlabSubscriptions::Trials::WelcomeCreateService).to receive(:new).and_wrap_original do |method, args|
+          expect(args[:params].to_h).to eq(params)
+          instance = method.call(**args)
+
+          result = ServiceResponse.success(
+            message: 'Trial applied',
+            payload: { namespace_id: namespace_id, project_id: project_id, add_on_purchase: add_on_purchase }
+          )
+          expect(instance).to receive(:execute).and_return(result)
+          instance
+        end
+
+        expect(post_create).to redirect_to(namespace_project_learn_gitlab_path(namespace_id, project_id))
+      end
+
+      it "when group creation fails" do
+        expect(GitlabSubscriptions::Trials::WelcomeCreateService).to receive(:new).and_wrap_original do |method, args|
+          expect(args[:params].to_h).to eq(params)
+          instance = method.call(**args)
+
+          result = ServiceResponse.error(
+            message: 'Trial creation failed in namespace stage',
+            payload: { namespace_id: nil, project_id: nil, lead_created: false,
+                       model_errors: [groupName: ["group creation failed"]] }
+          )
+          expect(instance).to receive(:execute).and_return(result)
+          instance
+        end
+
+        post_create
+
+        expect(response).to have_gitlab_http_status(:ok)
+        expect(response.body).to include(_('group creation failed'))
+      end
+
+      it "when user can not create a group" do
+        expect(GitlabSubscriptions::Trials::WelcomeCreateService).to receive(:new).and_wrap_original do |method, args|
+          expect(args[:params].to_h).to eq(params)
+          instance = method.call(**args)
+
+          result = ServiceResponse.error(
+            message: 'Trial creation failed in namespace stage',
+            reason: GitlabSubscriptions::Trials::UltimateCreateService::NOT_FOUND
+          )
+          expect(instance).to receive(:execute).and_return(result)
+          instance
+        end
+
+        expect(post_create).to have_gitlab_http_status(:not_found)
+      end
+
+      it "when project creation fails" do
+        expect(GitlabSubscriptions::Trials::WelcomeCreateService).to receive(:new).and_wrap_original do |method, args|
+          expect(args[:params].to_h).to eq(params)
+          instance = method.call(**args)
+
+          result = ServiceResponse.error(
+            message: 'Trial creation failed in project stage',
+            payload: { namespace_id: namespace_id, project_id: nil, lead_created: false,
+                       model_errors: [projectName: ["project creation failed"]] }
+          )
+          expect(instance).to receive(:execute).and_return(result)
+          instance
+        end
+
+        expect(post_create).to have_gitlab_http_status(:ok)
+        expect(response.body).to include(_('project creation failed'))
+      end
+
+      context "when resubmission" do
+        let(:params) { default_params.merge(namespace_id: namespace_id) }
+
+        it "when project creation success" do
+          expect(GitlabSubscriptions::Trials::WelcomeCreateService).to receive(:new).and_wrap_original do |method, args|
+            expect(args[:params].to_h).to eq(params.without(:namespace_id))
+            instance = method.call(**args)
+
+            result = ServiceResponse.success(
+              message: 'Trial applied',
+              payload: { namespace_id: namespace_id, project_id: project_id, lead_created: true }
+            )
+            expect(instance).to receive(:execute).and_return(result)
+            instance
+          end
+
+          expect(post_create).to redirect_to(namespace_project_learn_gitlab_path(namespace_id, project_id))
+        end
+      end
+    end
+  end
 end
diff --git a/ee/spec/services/gitlab_subscriptions/trials/welcome_create_service_spec.rb b/ee/spec/services/gitlab_subscriptions/trials/welcome_create_service_spec.rb
index fe98cba2fe112853672ff05c873b5e3f20e8c972..4ad6df2a693f1d8523c08fdfc6d0682d6edaaaff 100644
--- a/ee/spec/services/gitlab_subscriptions/trials/welcome_create_service_spec.rb
+++ b/ee/spec/services/gitlab_subscriptions/trials/welcome_create_service_spec.rb
@@ -201,7 +201,7 @@
         expect(execute).to be_error
         expect(execute.message).to eq("Trial creation failed in namespace stage")
         expect(execute.payload).to include({ namespace_id: nil, project_id: nil, lead_created: false })
-        expect(execute.payload.dig(:model_errors, :group)).to include(/^Name can't be blank/)
+        expect(execute.payload.dig(:model_errors, :group_name)).to include(/^Name can't be blank/)
       end
     end
 
@@ -215,7 +215,7 @@
         expect(execute).to be_error
         expect(execute.message).to eq("Trial creation failed in project stage")
         expect(execute.payload).to include({ namespace_id: Group.last.id, project_id: nil, lead_created: false })
-        expect(execute.payload.dig(:model_errors, :project)).to include(/^Name can't be blank/)
+        expect(execute.payload.dig(:model_errors, :project_name)).to include(/name can't be blank/)
       end
     end