diff --git a/db/docs/uploads_9ba88c4165.yml b/db/docs/uploads_9ba88c4165.yml
index 7b10c7e1264f953799ae89e7c18f07a3d48732fe..4ac098be77256bac51c3f639df2c436d0eef1296 100644
--- a/db/docs/uploads_9ba88c4165.yml
+++ b/db/docs/uploads_9ba88c4165.yml
@@ -16,4 +16,9 @@ introduced_by_url:
 milestone: '17.11'
 gitlab_schema: gitlab_main_org
 sharding_key_issue_url: https://gitlab.com/gitlab-org/gitlab/-/issues/398199
+sharding_key:
+  organization_id: organizations
+  namespace_id: namespaces
+  project_id: projects
+  uploaded_by_user_id: users
 table_size: small
diff --git a/db/post_migrate/20251206120000_add_uploads_sharding_key_constraint.rb b/db/post_migrate/20251206120000_add_uploads_sharding_key_constraint.rb
new file mode 100644
index 0000000000000000000000000000000000000000..eeb457916fcb83a3dd2ee198e2d18c4d10bbd4ea
--- /dev/null
+++ b/db/post_migrate/20251206120000_add_uploads_sharding_key_constraint.rb
@@ -0,0 +1,20 @@
+# frozen_string_literal: true
+
+class AddUploadsShardingKeyConstraint < Gitlab::Database::Migration[2.3]
+  milestone '18.7'
+  disable_ddl_transaction!
+
+  def up
+    add_multi_column_not_null_constraint(
+      :uploads_9ba88c4165,
+      :organization_id, :namespace_id, :project_id, :uploaded_by_user_id
+    )
+  end
+
+  def down
+    remove_multi_column_not_null_constraint(
+      :uploads_9ba88c4165,
+      :organization_id, :namespace_id, :project_id, :uploaded_by_user_id
+    )
+  end
+end
diff --git a/db/schema_migrations/20251206120000 b/db/schema_migrations/20251206120000
new file mode 100644
index 0000000000000000000000000000000000000000..dae055554b04a66d1d1fab37dd074e326a154556
--- /dev/null
+++ b/db/schema_migrations/20251206120000
@@ -0,0 +1 @@
+da68f96d8a4dc82b17bcd6484b09b737822bfa7b51319b4cd0953263570e2ca4
\ No newline at end of file
diff --git a/db/structure.sql b/db/structure.sql
index 39a58ec570850185d08755946ed51475164150e0..c7a51eb84d8ac3d59abaf25bc24e2c0827e31cf3 100644
--- a/db/structure.sql
+++ b/db/structure.sql
@@ -10596,7 +10596,8 @@ CREATE TABLE uploads_9ba88c4165 (
     mount_point text,
     secret text,
     CONSTRAINT check_2849dedce7 CHECK ((char_length(path) <= 511)),
-    CONSTRAINT check_b888b1df14 CHECK ((char_length(checksum) <= 64))
+    CONSTRAINT check_b888b1df14 CHECK ((char_length(checksum) <= 64)),
+    CONSTRAINT check_f4b854bf62 CHECK ((num_nonnulls(namespace_id, organization_id, project_id, uploaded_by_user_id) = 1))
 )
 PARTITION BY LIST (model_type);
 
diff --git a/spec/lib/gitlab/database/sharding_key_spec.rb b/spec/lib/gitlab/database/sharding_key_spec.rb
index f37a510e271a37e187065b25452a48f4d3b6c67b..e2707e8993bff0acce1d85ec8e666cc92f1da795 100644
--- a/spec/lib/gitlab/database/sharding_key_spec.rb
+++ b/spec/lib/gitlab/database/sharding_key_spec.rb
@@ -11,7 +11,6 @@
     [
       'ai_settings', # https://gitlab.com/gitlab-org/gitlab/-/issues/531356
       'web_hook_logs_daily', # temporary copy of web_hook_logs
-      'uploads_9ba88c4165', # https://gitlab.com/gitlab-org/gitlab/-/issues/398199
       'merge_request_diff_files_99208b8fac', # has a desired sharding key instead
       'award_emoji_archived', # temp table: https://gitlab.com/gitlab-org/gitlab/-/issues/580326
       'authentication_event_archived_records' # temp table: https://gitlab.com/gitlab-org/gitlab/-/merge_requests/202447