diff --git a/.changeset/small-shirts-lose.md b/.changeset/small-shirts-lose.md
new file mode 100644
index 0000000000..2fe3d6c414
--- /dev/null
+++ b/.changeset/small-shirts-lose.md
@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-catalog-backend-module-gitlab': patch
+---
+
+Fixed GitLab search API scope parameter from `'blob'` to `'blobs'`, resolving 400 errors in discovery provider.
diff --git a/plugins/catalog-backend-module-gitlab/src/__testUtils__/handlers.ts b/plugins/catalog-backend-module-gitlab/src/__testUtils__/handlers.ts
index 16adb01c10..e5b9b39ecd 100644
--- a/plugins/catalog-backend-module-gitlab/src/__testUtils__/handlers.ts
+++ b/plugins/catalog-backend-module-gitlab/src/__testUtils__/handlers.ts
@@ -201,7 +201,13 @@ const httpGroupFindByEncodedPathDynamic = all_groups_response.flatMap(group => [
 const httpSearchFilesInGroupDynamic = all_groups_response.map(group => {
   return rest.get(
     `${apiBaseUrl}/groups/${encodeURIComponent(group.full_path)}/search`,
-    (_, res, ctx) => {
+    (req, res, ctx) => {
+      const scope = req.url.searchParams.get('scope');
+
+      if (scope !== 'blobs') {
+        return res(ctx.status(400), ctx.text('400 Bad Request'));
+      }
+
       const searchResults = projects_with_catalog_info_yaml
         .filter(project =>
           project.path_with_namespace?.startsWith(group.full_path),
diff --git a/plugins/catalog-backend-module-gitlab/src/lib/client.test.ts b/plugins/catalog-backend-module-gitlab/src/lib/client.test.ts
index 60974d2d0f..5e10fbffd6 100644
--- a/plugins/catalog-backend-module-gitlab/src/lib/client.test.ts
+++ b/plugins/catalog-backend-module-gitlab/src/lib/client.test.ts
@@ -280,6 +280,67 @@ describe('GitLabClient', () => {
     });
   });
 
+  describe('listFiles', () => {
+    it('should call group search API with correct scope parameter', async () => {
+      const client = new GitLabClient({
+        config: readGitLabIntegrationConfig(
+          new ConfigReader(mock.config_self_managed),
+        ),
+        logger: mockServices.logger.mock(),
+      });
+
+      const pagedRequestSpy = jest.spyOn(client as any, 'pagedRequest');
+
+      await client.listFiles({
+        group: 'group1',
+        search: 'filename:catalog-info.yaml',
+        page: 1,
+        per_page: 50,
+      });
+
+      expect(pagedRequestSpy).toHaveBeenCalledWith(
+        '/groups/group1/search',
+        expect.objectContaining({
+          group: 'group1',
+          search: 'filename:catalog-info.yaml',
+          scope: 'blobs',
+          page: 1,
+          per_page: 50,
+        }),
+      );
+    });
+
+    it('should return empty items when group is missing', async () => {
+      const client = new GitLabClient({
+        config: readGitLabIntegrationConfig(
+          new ConfigReader(mock.config_self_managed),
+        ),
+        logger: mockServices.logger.mock(),
+      });
+
+      const result = await client.listFiles({
+        search: 'filename:catalog-info.yaml',
+      });
+
+      expect(result.items).toEqual([]);
+    });
+
+    it('should return empty items when search is missing', async () => {
+      const client = new GitLabClient({
+        config: readGitLabIntegrationConfig(
+          new ConfigReader(mock.config_self_managed),
+        ),
+        logger: mockServices.logger.mock(),
+      });
+
+      const result = await client.listFiles({
+        group: 'my-group',
+      });
+
+      expect(result.items).toEqual([]);
+    });
+  });
+
   describe('get gitlab.com users', () => {
     it('gets all users under group', async () => {
       const client = new GitLabClient({
diff --git a/plugins/catalog-backend-module-gitlab/src/lib/client.ts b/plugins/catalog-backend-module-gitlab/src/lib/client.ts
index 4f220deb68..c04585142d 100644
--- a/plugins/catalog-backend-module-gitlab/src/lib/client.ts
+++ b/plugins/catalog-backend-module-gitlab/src/lib/client.ts
@@ -185,7 +185,7 @@ export class GitLabClient {
         `/groups/${encodeURIComponent(options?.group)}/search`,
         {
           ...options,
-          scope: 'blob',
+          scope: 'blobs',
         },
       );
     }