diff --git a/.changeset/quiet-needles-impress.md b/.changeset/quiet-needles-impress.md
new file mode 100644
index 0000000000..a79fe97b91
--- /dev/null
+++ b/.changeset/quiet-needles-impress.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-scaffolder-backend-module-gitlab': minor
+---
+
+declare correct type (number) for publish:gitlab output.projectId
diff --git a/plugins/scaffolder-backend-module-gitlab/src/actions/gitlab.ts b/plugins/scaffolder-backend-module-gitlab/src/actions/gitlab.ts
index 020e8a9c18..1c888cff09 100644
--- a/plugins/scaffolder-backend-module-gitlab/src/actions/gitlab.ts
+++ b/plugins/scaffolder-backend-module-gitlab/src/actions/gitlab.ts
@@ -294,7 +294,7 @@ export function createPublishGitlabAction(options: {
           },
           projectId: {
             title: 'The ID of the project',
-            type: 'string',
+            type: 'number',
           },
           commitHash: {
             title: 'The git commit hash of the initial commit',