diff --git a/api/app/settings/common.py b/api/app/settings/common.py
index 027d029f085d..25b9669a8037 100644
--- a/api/app/settings/common.py
+++ b/api/app/settings/common.py
@@ -648,7 +648,7 @@
 CACHE_FLAGS_SECONDS = env.int("CACHE_FLAGS_SECONDS", default=0)
 FLAGS_CACHE_LOCATION = "environment-flags"
 CHARGEBEE_CACHE_LOCATION = "chargebee-objects"
-
+CACHE_KEY_PREFIX = env.str("CACHE_KEY_PREFIX", default="")
 ENVIRONMENT_CACHE_SECONDS = env.int("ENVIRONMENT_CACHE_SECONDS", default=60)
 ENVIRONMENT_CACHE_BACKEND = env.str(
     "ENVIRONMENT_CACHE_BACKEND",
@@ -1037,7 +1037,11 @@
         subcast=str,
         default=[],
     )
-
+# Apply key prefix to all Redis-backed caches to support
+# ACL-based multi-tenancy on shared Redis instances.
+for _cache_config in CACHES.values():
+    if "redis" in _cache_config.get("BACKEND", "").lower():  # type: ignore[attr-defined]
+        _cache_config["KEY_PREFIX"] = CACHE_KEY_PREFIX  # type: ignore[index]
 
 WORKFLOWS_LOGIC_INSTALLED = importlib.util.find_spec("workflows_logic") is not None
 
diff --git a/api/tests/unit/app/test_unit_app_settings.py b/api/tests/unit/app/test_unit_app_settings.py
new file mode 100644
index 000000000000..9cc5a1e0e552
--- /dev/null
+++ b/api/tests/unit/app/test_unit_app_settings.py
@@ -0,0 +1,51 @@
+import pytest
+
+
+def test_cache_key_prefix__redis_backend__key_prefix_applied(
+    monkeypatch: pytest.MonkeyPatch,
+) -> None:
+    # Given
+    prefix = "flagsmith"
+    caches = {
+        "redis_cache": {
+            "BACKEND": "django_redis.cache.RedisCache",
+            "LOCATION": "redis://localhost:6379/1",
+        },
+        "locmem_cache": {
+            "BACKEND": "django.core.cache.backends.locmem.LocMemCache",
+            "LOCATION": "test",
+        },
+        "db_cache": {
+            "BACKEND": "django.core.cache.backends.db.DatabaseCache",
+            "LOCATION": "cache_table",
+        },
+    }
+
+    # When - same logic as settings
+    for cache_config in caches.values():
+        if "redis" in cache_config.get("BACKEND", "").lower():
+            cache_config["KEY_PREFIX"] = prefix
+
+    # Then
+    assert caches["redis_cache"]["KEY_PREFIX"] == prefix
+    assert "KEY_PREFIX" not in caches["locmem_cache"]
+    assert "KEY_PREFIX" not in caches["db_cache"]
+
+
+def test_cache_key_prefix__empty_prefix__redis_backend_gets_empty_prefix() -> None:
+    # Given
+    prefix = ""
+    caches = {
+        "redis_cache": {
+            "BACKEND": "django_redis.cache.RedisCache",
+            "LOCATION": "redis://localhost:6379/1",
+        },
+    }
+
+    # When
+    for cache_config in caches.values():
+        if "redis" in cache_config.get("BACKEND", "").lower():
+            cache_config["KEY_PREFIX"] = prefix
+
+    # Then
+    assert caches["redis_cache"]["KEY_PREFIX"] == ""