diff --git a/litellm/proxy/utils.py b/litellm/proxy/utils.py
index c095586b6c9..59ebd648a09 100644
--- a/litellm/proxy/utils.py
+++ b/litellm/proxy/utils.py
@@ -5386,6 +5386,14 @@ class PrismaClient:
     def _is_engine_alive(self) -> bool:
         if self._engine_pid <= 0:
             return True
+        # Windows 上 os.kill(pid, 0) 不是 Unix 的「signal-0 存活探測」，而是直接
+        # 呼叫 TerminateProcess(handle, 0) 把 engine 殺掉：CPython 在 Windows 只
+        # 把 CTRL_C_EVENT / CTRL_BREAK_EVENT 當特例，其餘 sig 值（含 0）一律
+        # TerminateProcess。Windows 沒有安全的 signal-0 探測方式，故一律回報存活，
+        # 真正的 engine 故障交由查詢層 call_with_db_reconnect_retry 在
+        # ReadError / ConnectError 時惰性處理。
+        if sys.platform == "win32":
+            return True
         try:
             os.kill(self._engine_pid, 0)
             return True
@@ -5610,6 +5618,11 @@ class PrismaClient:
         Only used when BOTH waitpid thread and pidfd are unavailable
         (e.g., PID is not our child process and pidfd_open fails)
         """
+        # 保險絲：Windows 上 os.kill(pid, 0) 會 TerminateProcess 殺掉 engine，
+        # 這個 poller 絕不能在 Windows 執行。_start_engine_watcher 已在 win32
+        # 不會排這個 task，此處再擋一道以防未來有其他呼叫點。
+        if sys.platform == "win32":
+            return
         while self._watching_engine and self._engine_pid > 0:
             try:
                 os.kill(self._engine_pid, 0)
@@ -5692,6 +5705,18 @@ class PrismaClient:
                 "Watching engine PID %s via pidfd.",
                 pid,
             )
+        elif sys.platform == "win32":
+            # Windows 沒有 waitpid/pidfd，唯一的 fallback 是 os.kill 輪詢，但
+            # os.kill(pid, 0) 在 Windows 會 TerminateProcess 把 engine 殺掉
+            # （連上後約 1 秒就被自己的存活檢查殺死，之後所有查詢 ConnectError）。
+            # 因此 Windows 不做主動 engine-death 偵測——回到 1.82 之前 Windows 的
+            # 既有行為，engine 故障由查詢層的 reconnect retry 惰性處理。
+            verbose_proxy_logger.info(
+                "Engine PID %s: proactive engine-death detection is unavailable on "
+                "Windows (waitpid/pidfd unsupported; os.kill polling would terminate "
+                "the engine). Relying on query-level reconnect retry instead.",
+                pid,
+            )
         else:
             verbose_proxy_logger.info(
                 "Watching engine PID %s via os.kill polling.",
diff --git a/tests/test_litellm/proxy/utils/prisma_and_spend/test_prisma_client_engine_watcher.py b/tests/test_litellm/proxy/utils/prisma_and_spend/test_prisma_client_engine_watcher.py
index 25c04caabba..7446bd4c4be 100644
--- a/tests/test_litellm/proxy/utils/prisma_and_spend/test_prisma_client_engine_watcher.py
+++ b/tests/test_litellm/proxy/utils/prisma_and_spend/test_prisma_client_engine_watcher.py
@@ -712,3 +712,73 @@ async def test_poll_engine_proc_planned_death_skips_reconnect(
         "cleanup_called": 1,
         "confirmed_dead": False,
     }
+
+
+# ---------------------------------------------------------------------------
+# Windows: os.kill(pid, 0) is NOT a liveness probe -- CPython maps every sig
+# other than CTRL_C_EVENT/CTRL_BREAK_EVENT (including 0) to TerminateProcess,
+# so the Unix-style liveness checks would terminate the query engine (~1s after
+# connect, then every subsequent query fails with ConnectError). The engine
+# watcher therefore must never signal the engine on Windows. These tests run on
+# the Linux CI runner and simulate Windows by patching ``sys.platform`` -- the
+# module-level ``skipif(win32)`` above keeps them from running on real Windows
+# where ``os.kill`` would actually kill the test's own processes.
+# ---------------------------------------------------------------------------
+def test_is_engine_alive_never_calls_os_kill_on_windows(
+    prisma_client: PrismaClient, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    prisma_client._engine_pid = 12345
+    fake_kill = MagicMock()
+    monkeypatch.setattr("os.kill", fake_kill)
+    monkeypatch.setattr(sys, "platform", "win32")
+    pinned = {
+        "result": prisma_client._is_engine_alive(),
+        "os_kill_calls": fake_kill.call_count,
+    }
+    assert pinned == {"result": True, "os_kill_calls": 0}
+
+
+@pytest.mark.asyncio
+async def test_poll_engine_proc_is_noop_on_windows(
+    prisma_client: PrismaClient, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    prisma_client._engine_pid = 555
+    prisma_client._watching_engine = True
+    prisma_client.attempt_db_reconnect = AsyncMock()
+    fake_kill = MagicMock()
+    monkeypatch.setattr("os.kill", fake_kill)
+    monkeypatch.setattr(sys, "platform", "win32")
+
+    # Must return immediately without ever signalling the engine.
+    await asyncio.wait_for(prisma_client._poll_engine_proc(), timeout=1)
+    pinned = {
+        "os_kill_calls": fake_kill.call_count,
+        "reconnect_calls": prisma_client.attempt_db_reconnect.await_count,
+    }
+    assert pinned == {"os_kill_calls": 0, "reconnect_calls": 0}
+
+
+@pytest.mark.asyncio
+async def test_start_engine_watcher_does_not_poll_on_windows(
+    prisma_client: PrismaClient, monkeypatch: pytest.MonkeyPatch
+) -> None:
+    """On Windows both waitpid and pidfd are unavailable; the watcher must NOT
+    fall back to os.kill polling (which would terminate the engine). It records
+    the PID but starts no poller, deferring to query-level reconnect retry."""
+    monkeypatch.setattr(prisma_client, "_get_engine_pid", MagicMock(return_value=4242))
+    monkeypatch.setattr(prisma_client, "_try_waitpid_watch", MagicMock(return_value=False))
+    monkeypatch.setattr(prisma_client, "_try_pidfd_watch", MagicMock(return_value=False))
+    poll = AsyncMock()
+    monkeypatch.setattr(prisma_client, "_poll_engine_proc", poll)
+    fake_kill = MagicMock()
+    monkeypatch.setattr("os.kill", fake_kill)
+    monkeypatch.setattr(sys, "platform", "win32")
+
+    await prisma_client._start_engine_watcher()
+    await asyncio.sleep(0)
+    pinned = {
+        "watching": prisma_client._watching_engine,
+        "poll_started": poll.await_count,
+        "os_kill_calls": fake_kill.call_count,
+    }
+    assert pinned == {"watching": False, "poll_started": 0, "os_kill_calls": 0}