diff --git a/CHANGELOG.md b/CHANGELOG.md
index e69de29bb2d..193b95725e8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -0,0 +1 @@
+- Enable [preferRest](https://firebase.google.com/docs/reference/admin/node/firebase-admin.firestore.firestoresettings.md#firestoresettingspreferrest) option by default for Firestore functions. (#6147)
diff --git a/src/functions/env.ts b/src/functions/env.ts
index b640aff443e..92cc4f19492 100644
--- a/src/functions/env.ts
+++ b/src/functions/env.ts
@@ -410,5 +410,6 @@ export function loadFirebaseEnvs(
   return {
     FIREBASE_CONFIG: JSON.stringify(firebaseConfig),
     GCLOUD_PROJECT: projectId,
+    FIRESTORE_PREFER_REST: "true",
   };
 }