diff --git a/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.test.ts b/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.test.ts
new file mode 100644
index 000000000..b18d94740
--- /dev/null
+++ b/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.test.ts
@@ -0,0 +1,107 @@
+import { beforeEach, describe, expect, it, mock } from "bun:test";
+
+const workspaceFindFirst = mock();
+const customDomainFindFirst = mock();
+const customDomainDeleteMany = mock();
+const kyDelete = mock();
+
+process.env.SKIP_ENV_CHECK = "true";
+process.env.ENCRYPTION_SECRET = "12345678901234567890123456789012";
+process.env.NEXTAUTH_URL = "https://app.typebot.io";
+process.env.NEXT_PUBLIC_VERCEL_VIEWER_PROJECT_NAME = "viewer-project";
+process.env.VERCEL_TEAM_ID = "team-id";
+process.env.VERCEL_TOKEN = "vercel-token";
+
+mock.module("@typebot.io/lib/ky", () => ({
+  ky: {
+    delete: kyDelete,
+  },
+}));
+
+mock.module("@typebot.io/prisma", () => ({
+  default: {
+    workspace: {
+      findFirst: workspaceFindFirst,
+    },
+    customDomain: {
+      findFirst: customDomainFindFirst,
+      deleteMany: customDomainDeleteMany,
+    },
+  },
+}));
+
+const { handleDeleteCustomDomain } = await import("./handleDeleteCustomDomain");
+
+describe("handleDeleteCustomDomain", () => {
+  beforeEach(() => {
+    workspaceFindFirst.mockReset();
+    customDomainFindFirst.mockReset();
+    customDomainDeleteMany.mockReset();
+    kyDelete.mockReset();
+
+    workspaceFindFirst.mockResolvedValue({
+      members: [{ userId: "user-id", role: "ADMIN" }],
+    });
+    kyDelete.mockResolvedValue({});
+    customDomainDeleteMany.mockResolvedValue({ count: 1 });
+  });
+
+  it("does not delete an external domain when it is not owned by the workspace", async () => {
+    customDomainFindFirst.mockResolvedValue(null);
+
+    await expect(
+      handleDeleteCustomDomain({
+        input: {
+          workspaceId: "workspace-id",
+          name: "other-workspace.example.com",
+        },
+        context: {
+          user: { id: "user-id" },
+        },
+      }),
+    ).rejects.toBeDefined();
+
+    expect(customDomainFindFirst).toHaveBeenCalledWith({
+      where: {
+        name: "other-workspace.example.com",
+        workspaceId: "workspace-id",
+      },
+      select: {
+        name: true,
+      },
+    });
+    expect(kyDelete).not.toHaveBeenCalled();
+    expect(customDomainDeleteMany).not.toHaveBeenCalled();
+  });
+
+  it("deletes an owned external domain and the matching database record", async () => {
+    customDomainFindFirst.mockResolvedValue({
+      name: "owned.example.com",
+    });
+
+    await expect(
+      handleDeleteCustomDomain({
+        input: {
+          workspaceId: "workspace-id",
+          name: "owned.example.com",
+        },
+        context: {
+          user: { id: "user-id" },
+        },
+      }),
+    ).resolves.toEqual({ message: "success" });
+
+    expect(kyDelete).toHaveBeenCalledWith(
+      "https://api.vercel.com/v9/projects/viewer-project/domains/owned.example.com?teamId=team-id",
+      {
+        headers: { Authorization: "Bearer vercel-token" },
+      },
+    );
+    expect(customDomainDeleteMany).toHaveBeenCalledWith({
+      where: {
+        name: "owned.example.com",
+        workspaceId: "workspace-id",
+      },
+    });
+  });
+});
diff --git a/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.ts b/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.ts
index 2296ee27d..00990c831 100644
--- a/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.ts
+++ b/apps/builder/src/features/customDomains/api/handleDeleteCustomDomain.ts
@@ -34,8 +34,21 @@ export const handleDeleteCustomDomain = async ({
   if (!workspace || isWriteWorkspaceForbidden(workspace, user))
     throw new ORPCError("NOT_FOUND", { message: "Workspace not found" });
 
+  const customDomain = await prisma.customDomain.findFirst({
+    where: {
+      name,
+      workspaceId,
+    },
+    select: {
+      name: true,
+    },
+  });
+
+  if (!customDomain)
+    throw new ORPCError("NOT_FOUND", { message: "Custom domain not found" });
+
   try {
-    await deleteDomainOnVercel(name);
+    await deleteDomainOnVercel(customDomain.name);
   } catch (error) {
     console.error(error);
     if (error instanceof HTTPError)
@@ -50,7 +63,7 @@ export const handleDeleteCustomDomain = async ({
   }
   await prisma.customDomain.deleteMany({
     where: {
-      name,
+      name: customDomain.name,
       workspaceId,
     },
   });