diff --git a/db/docs/batched_background_migrations/backfill_merge_request_cleanup_schedules_project_id.yml b/db/docs/batched_background_migrations/backfill_merge_request_cleanup_schedules_project_id.yml
index a93d6f33a6e67b6fdc715ce9759046246439cdc6..257ec5924938ad475bbc0604c164a984bc6eb989 100644
--- a/db/docs/batched_background_migrations/backfill_merge_request_cleanup_schedules_project_id.yml
+++ b/db/docs/batched_background_migrations/backfill_merge_request_cleanup_schedules_project_id.yml
@@ -1,8 +1,9 @@
 ---
 migration_job_name: BackfillMergeRequestCleanupSchedulesProjectId
-description: Backfills sharding key `merge_request_cleanup_schedules.project_id` from `merge_requests`.
+description: Backfills sharding key `merge_request_cleanup_schedules.project_id` from
+  `merge_requests`.
 feature_category: code_review_workflow
 introduced_by_url: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/180840
 milestone: '18.4'
 queued_migration_version: 20250820170760
-finalized_by: # version of the migration that finalized this BBM
+finalized_by: '20251021232133'
diff --git a/db/post_migrate/20251021232133_finalize_hk_backfill_merge_request_cleanup_schedules_project_id.rb b/db/post_migrate/20251021232133_finalize_hk_backfill_merge_request_cleanup_schedules_project_id.rb
new file mode 100644
index 0000000000000000000000000000000000000000..1a5cfe71b5605de15a260530ad51e24b64dce021
--- /dev/null
+++ b/db/post_migrate/20251021232133_finalize_hk_backfill_merge_request_cleanup_schedules_project_id.rb
@@ -0,0 +1,21 @@
+# frozen_string_literal: true
+
+class FinalizeHkBackfillMergeRequestCleanupSchedulesProjectId < Gitlab::Database::Migration[2.3]
+  milestone '18.6'
+
+  disable_ddl_transaction!
+
+  restrict_gitlab_migration gitlab_schema: :gitlab_main_org
+
+  def up
+    ensure_batched_background_migration_is_finished(
+      job_class_name: 'BackfillMergeRequestCleanupSchedulesProjectId',
+      table_name: :merge_request_cleanup_schedules,
+      column_name: :merge_request_id,
+      job_arguments: [:project_id, :merge_requests, :target_project_id, :merge_request_id],
+      finalize: true
+    )
+  end
+
+  def down; end
+end
diff --git a/db/schema_migrations/20251021232133 b/db/schema_migrations/20251021232133
new file mode 100644
index 0000000000000000000000000000000000000000..4fd3894f127ca7d97097216415364d7064f3c411
--- /dev/null
+++ b/db/schema_migrations/20251021232133
@@ -0,0 +1 @@
+f5bbb8074a8b41db8f5e5fd51eaa17bab6b43aaa07b326d5eb9eb0bcb97a121a
\ No newline at end of file