diff --git a/scripts/migrate.mjs b/scripts/migrate.mjs
index e2dd934..56e60cd 100644
--- a/scripts/migrate.mjs
+++ b/scripts/migrate.mjs
@@ -85,6 +85,16 @@ async function convertForeignKeys(sql) {
   `;
   console.log(`  commissioners.user_id: ${commissResult.count} rows converted`);
 
+  // Convert leagues.created_by from Clerk IDs to users.id UUIDs
+  const leaguesResult = await sql`
+    UPDATE leagues l
+    SET created_by = u.id::text
+    FROM users u
+    WHERE l.created_by = u.clerk_id
+      AND u.clerk_id IS NOT NULL
+  `;
+  console.log(`  leagues.created_by: ${leaguesResult.count} rows converted`);
+
   // Mark all Clerk users as email-verified (they already verified via Clerk)
   await sql`
     UPDATE users