diff --git a/plugins/platforms/whatsapp/adapter.py b/plugins/platforms/whatsapp/adapter.py
index add70f4d67..485608f991 100644
--- a/plugins/platforms/whatsapp/adapter.py
+++ b/plugins/platforms/whatsapp/adapter.py
@@ -225,7 +225,7 @@ _BRIDGE_PASSTHROUGH_ENV = (
     "WHATSAPP_ALLOWED_USERS", "WHATSAPP_ALLOW_FROM", "WHATSAPP_DM_POLICY", "WHATSAPP_GROUP_POLICY",
     "WHATSAPP_GROUP_ALLOWED_USERS", "WHATSAPP_GROUP_ALLOW_FROM", "WHATSAPP_REQUIRE_MENTION",
     "WHATSAPP_MENTION_PATTERNS", "WHATSAPP_FREE_RESPONSE_CHATS", "WHATSAPP_DEBUG",
-    "WHATSAPP_FORWARD_OWNER_MESSAGES", "WHATSAPP_REPLY_PREFIX", "WHATSAPP_MAX_MESSAGE_LENGTH",
+    "WHATSAPP_FORWARD_OWNER_MESSAGES", "WHATSAPP_MAX_MESSAGE_LENGTH",
     "WHATSAPP_CHUNK_DELAY_MS", "WHATSAPP_SEND_TIMEOUT_MS",
 )
 _TEXT_INJECT_EXTS = {".txt", ".md", ".csv", ".json", ".xml", ".yaml", ".yml", ".log", ".py", ".js", ".ts", ".html", ".css"}
@@ -375,8 +375,13 @@ class WhatsAppAdapter(WhatsAppBehaviorMixin, BasePlatformAdapter):
         # that copy carries the DEFAULT profile's WHATSAPP_* values, so every bridge-consumed key is
         # re-resolved from this profile (dropped on a scoped miss), never inherited from the launch env.
         bridge_env = with_hermes_node_path()
-        if self._reply_prefix is not None:
+        reply_prefix = _wenv("WHATSAPP_REPLY_PREFIX")
+        if reply_prefix:
+            bridge_env["WHATSAPP_REPLY_PREFIX"] = reply_prefix
+        elif self._reply_prefix is not None:
             bridge_env["WHATSAPP_REPLY_PREFIX"] = self._reply_prefix
+        else:
+            bridge_env.pop("WHATSAPP_REPLY_PREFIX", None)
         bridge_env["WHATSAPP_SEND_READ_RECEIPTS"] = "true" if self._send_read_receipts else "false"
         for _key, _v in [("WHATSAPP_MODE", _wenv("WHATSAPP_MODE", "self-chat"))] + [(k, _wenv(k)) for k in _BRIDGE_PASSTHROUGH_ENV]:
             if _v:
diff --git a/tests/gateway/test_adapter_settings_scoped_precedence.py b/tests/gateway/test_adapter_settings_scoped_precedence.py
index f4bd0d454f..dc9e05b91c 100644
--- a/tests/gateway/test_adapter_settings_scoped_precedence.py
+++ b/tests/gateway/test_adapter_settings_scoped_precedence.py
@@ -195,3 +195,38 @@ def test_whatsapp_bridge_env_carries_the_secondary_effective_policy(homes, monke
     assert a._group_policy == "allowlist" == env["WHATSAPP_GROUP_POLICY"]
     assert env["WHATSAPP_GROUP_ALLOWED_USERS"] == "120363001234567890@g.us"
     assert "WHATSAPP_ALLOWED_USERS" not in env
+
+
+@pytest.mark.parametrize("secondary_prefix", [None, "Secondary Bot: ", ""])
+def test_whatsapp_reply_prefix_isolated_across_profile_scopes(
+    homes, monkeypatch, secondary_prefix
+):
+    from plugins.platforms.whatsapp.adapter import WhatsAppAdapter
+
+    launch, secondary = homes
+    monkeypatch.setenv("WHATSAPP_REPLY_PREFIX", "Launch Bot: ")
+    (launch / "config.yaml").write_text(
+        'whatsapp:\n  enabled: true\n  reply_prefix: "Launch YAML: "\n'
+    )
+    launch_before = WhatsAppAdapter(
+        load_gateway_config().platforms[Platform.WHATSAPP]
+    )
+    assert launch_before._bridge_env()["WHATSAPP_REPLY_PREFIX"] == "Launch Bot: "
+
+    secondary_yaml = "whatsapp:\n  enabled: true\n"
+    if secondary_prefix is not None:
+        secondary_yaml += f'  reply_prefix: "{secondary_prefix}"\n'
+    (secondary / "config.yaml").write_text(secondary_yaml)
+    with _secondary_scope(secondary):
+        secondary_adapter = WhatsAppAdapter(
+            load_gateway_config().platforms[Platform.WHATSAPP]
+        )
+        assert (
+            secondary_adapter._bridge_env().get("WHATSAPP_REPLY_PREFIX")
+            == secondary_prefix
+        )
+
+    launch_after = WhatsAppAdapter(
+        load_gateway_config().platforms[Platform.WHATSAPP]
+    )
+    assert launch_after._bridge_env()["WHATSAPP_REPLY_PREFIX"] == "Launch Bot: "
diff --git a/tests/gateway/test_whatsapp_reply_prefix.py b/tests/gateway/test_whatsapp_reply_prefix.py
index 26a008c2b0..c67a0fefb1 100644
--- a/tests/gateway/test_whatsapp_reply_prefix.py
+++ b/tests/gateway/test_whatsapp_reply_prefix.py
@@ -83,6 +83,31 @@ class TestAdapterInit:
         assert adapter._reply_prefix == "Bot\\n"
 
 
+class TestBridgeEnvironment:
+    @pytest.mark.parametrize(
+        ("configured", "explicit_env", "expected"),
+        [
+            ("Custom Bot\\n", None, "Custom Bot\\n"),
+            ("", None, ""),
+            ("Config Bot\\n", "Env Bot\\n", "Env Bot\\n"),
+        ],
+    )
+    def test_reply_prefix_reaches_bridge_with_existing_precedence(
+        self, monkeypatch, configured, explicit_env, expected
+    ):
+        from plugins.platforms.whatsapp.adapter import WhatsAppAdapter
+
+        monkeypatch.delenv("WHATSAPP_REPLY_PREFIX", raising=False)
+        if explicit_env is not None:
+            monkeypatch.setenv("WHATSAPP_REPLY_PREFIX", explicit_env)
+
+        adapter = WhatsAppAdapter(
+            PlatformConfig(enabled=True, extra={"reply_prefix": configured})
+        )
+
+        assert adapter._bridge_env()["WHATSAPP_REPLY_PREFIX"] == expected
+
+
 class TestReadReceiptPolicyOrdering:
     @pytest.mark.asyncio
     async def test_accepted_receipt_key_is_sent_to_bridge(self):