diff --git a/plugins/platforms/telegram/adapter.py b/plugins/platforms/telegram/adapter.py
index a852b7b830..00dbba0b59 100644
--- a/plugins/platforms/telegram/adapter.py
+++ b/plugins/platforms/telegram/adapter.py
@@ -33,6 +33,23 @@ def _redact_telegram_error_text(error: object) -> str:
         return "<telegram error redacted>"
 
 
+def _decode_json_list_literal(raw):
+    """Decode a JSON-encoded allowlist written by ``hermes config set``.
+
+    String-typed defaults keep list literals verbatim on write (``allowed_chats`` is
+    declared as ``""``), so the config can hold ``'["-100","-200"]'`` as a string.
+    Malformed JSON passes through unchanged and keeps the legacy comma-split path.
+    """
+    if isinstance(raw, str) and raw.lstrip()[:1] == "[":
+        try:
+            loaded = json.loads(raw)
+        except ValueError:
+            return raw
+        if isinstance(loaded, list):
+            return loaded
+    return raw
+
+
 def _consume_abandoned_task(task: asyncio.Task) -> None:
     """Observe a detached task's terminal exception to avoid noisy loop logs."""
     try:
@@ -5058,6 +5075,7 @@ class TelegramAdapter(BasePlatformAdapter):
         raw = self.config.extra.get(key)
         if raw is None:
             raw = _scoped_gate_env(env_name)
+        raw = _decode_json_list_literal(raw)
         if isinstance(raw, list):
             return {str(part).strip() for part in raw if str(part).strip()}
         return {part.strip() for part in str(raw).split(",") if part.strip()}
@@ -5131,6 +5149,7 @@ class TelegramAdapter(BasePlatformAdapter):
         raw = self.config.extra.get("ignored_threads")
         if raw is None:
             raw = _scoped_gate_env("TELEGRAM_IGNORED_THREADS")
+        raw = _decode_json_list_literal(raw)
         ignored: set[int] = set()
         for value in (raw if isinstance(raw, list) else str(raw).split(",")):
             text = str(value).strip()
diff --git a/tests/gateway/test_telegram_allowlist_json.py b/tests/gateway/test_telegram_allowlist_json.py
new file mode 100644
index 0000000000..a6cdc54fe3
--- /dev/null
+++ b/tests/gateway/test_telegram_allowlist_json.py
@@ -0,0 +1,83 @@
+import json
+from types import SimpleNamespace
+
+from gateway.config import Platform, PlatformConfig
+
+
+def _make_json_adapter(allowed_chats):
+    from plugins.platforms.telegram.adapter import TelegramAdapter
+
+    extra = {
+        "allowed_chats": allowed_chats,
+        "allowed_topics": [],
+        "group_allowed_chats": [],
+    }
+    adapter = object.__new__(TelegramAdapter)
+    adapter.platform = Platform.TELEGRAM
+    adapter.config = PlatformConfig(enabled=True, token="***", extra=extra)
+    adapter._bot = SimpleNamespace(id=999, username="hermes_bot")
+    return adapter
+
+
+def _group_msg(chat_id=-100):
+    return SimpleNamespace(
+        message_id=42,
+        text="hello",
+        caption=None,
+        entities=[],
+        caption_entities=[],
+        message_thread_id=None,
+        chat=SimpleNamespace(id=chat_id, type="group", title="G", is_forum=False),
+        from_user=SimpleNamespace(id=111, full_name="A B", first_name="A"),
+        reply_to_message=None,
+        date=None,
+    )
+
+
+def test_allowed_chats_json_string_parses_as_allowlist():
+    adapter = _make_json_adapter('["-100","-200"]')
+    assert adapter._telegram_allowed_chats() == {"-100", "-200"}
+
+
+def test_allowed_chats_json_string_end_to_end_gating():
+    adapter = _make_json_adapter(json.dumps(["-100"]))
+    assert adapter._should_process_message(_group_msg(chat_id=-100)) is True
+    assert adapter._should_process_message(_group_msg(chat_id=-300)) is False
+
+
+def test_allowed_chats_comma_string_still_works():
+    adapter = _make_json_adapter("-100,-200")
+    assert adapter._telegram_allowed_chats() == {"-100", "-200"}
+
+
+def test_allowed_chats_native_list_still_works():
+    adapter = _make_json_adapter(["-100", "-200"])
+    assert adapter._telegram_allowed_chats() == {"-100", "-200"}
+
+
+def test_allowed_chats_malformed_json_falls_back_to_comma_split():
+    adapter = _make_json_adapter('["-100", "-200')
+    assert adapter._telegram_allowed_chats() == {'["-100"', '"-200'}
+
+
+def test_ignored_threads_json_string_parses():
+    from plugins.platforms.telegram.adapter import TelegramAdapter
+
+    extra = {"ignored_threads": '["7", "9"]'}
+    adapter = object.__new__(TelegramAdapter)
+    adapter.platform = Platform.TELEGRAM
+    adapter.config = PlatformConfig(enabled=True, token="***", extra=extra)
+    adapter._bot = SimpleNamespace(id=999, username="hermes_bot")
+    assert adapter._telegram_ignored_threads() == {7, 9}
+
+
+def test_all_allowlist_keys_decode_json_string():
+    adapter = _make_json_adapter('["-100"]')
+    adapter.config.extra["group_allowed_chats"] = '["-300"]'
+    adapter.config.extra["allowed_topics"] = '["5"]'
+    adapter.config.extra["free_response_chats"] = '["-400"]'
+    adapter.config.extra["free_response_topics"] = '["-100:3"]'
+    assert adapter._telegram_group_allowed_chats() == {"-300"}
+    assert adapter._telegram_allowed_topics() == {"5"}
+    assert adapter._telegram_free_response_chats() == {"-400"}
+    assert adapter._telegram_free_response_topics() == {"-100:3"}