diff --git a/change/@starknet-react-core-1e21f5c8-df99-4f03-8737-a2c005200132.json b/change/@starknet-react-core-1e21f5c8-df99-4f03-8737-a2c005200132.json
new file mode 100644
index 00000000..b63fd307
--- /dev/null
+++ b/change/@starknet-react-core-1e21f5c8-df99-4f03-8737-a2c005200132.json
@@ -0,0 +1,7 @@
+{
+  "type": "patch",
+  "comment": "fix: paymaster api key header",
+  "packageName": "@starknet-react/core",
+  "email": "lenny@419labs.io",
+  "dependentChangeType": "patch"
+}
diff --git a/packages/core/src/providers/paymaster/avnu.ts b/packages/core/src/providers/paymaster/avnu.ts
index d76cceb7..13bd6221 100644
--- a/packages/core/src/providers/paymaster/avnu.ts
+++ b/packages/core/src/providers/paymaster/avnu.ts
@@ -16,7 +16,10 @@ export function avnuPaymasterProvider({
     rpc: (chain) => {
       const baseHttpUrl = chain.paymasterRpcUrls.avnu.http[0];
       if (!baseHttpUrl) return null;
-      return { nodeUrl: baseHttpUrl, headers: { "x-api-key": apiKey ?? "" } };
+      return {
+        nodeUrl: baseHttpUrl,
+        headers: { "x-paymaster-api-key": apiKey ?? "" },
+      };
     },
   });
 }