diff --git a/.changeset/fix-init-varlock-env-cached-path.md b/.changeset/fix-init-varlock-env-cached-path.md
new file mode 100644
index 00000000..b31775cc
--- /dev/null
+++ b/.changeset/fix-init-varlock-env-cached-path.md
@@ -0,0 +1,5 @@
+---
+"@varlock/nextjs-integration": patch
+---
+
+Fix: call `initVarlockEnv()` in the cached-env code path so the `ENV` proxy is properly initialized at runtime (e.g., on Vercel serverless), not just at build time.
diff --git a/packages/integrations/nextjs/src/next-env-compat.ts b/packages/integrations/nextjs/src/next-env-compat.ts
index 78234840..5ddcc88c 100644
--- a/packages/integrations/nextjs/src/next-env-compat.ts
+++ b/packages/integrations/nextjs/src/next-env-compat.ts
@@ -300,6 +300,7 @@ export function loadEnvConfig(
         Object.entries(varlockLoadedEnv.config).map(([key, value]) => [key, value.value]),
       );
 
+      initVarlockEnv();
       resetRedactionMap(varlockLoadedEnv);
       debug('patching console with varlock redactor');
       patchGlobalConsole();