diff --git a/ui/src/ui/views/debug.test.ts b/ui/src/ui/views/debug.test.ts
index 7fedbbf8bb9..7160336671a 100644
--- a/ui/src/ui/views/debug.test.ts
+++ b/ui/src/ui/views/debug.test.ts
@@ -72,4 +72,26 @@ describe("renderDebug", () => {
     );
     expect(command.textContent).toBe("openclaw security audit --deep");
   });
+
+  it("does not render Invalid Date for Date-invalid event timestamps", () => {
+    const container = document.createElement("div");
+
+    render(
+      renderDebug(
+        createProps({
+          eventLog: [
+            {
+              ts: 8_640_000_000_000_001,
+              event: "gateway",
+              payload: { ok: true },
+            },
+          ],
+        }),
+      ),
+      container,
+    );
+
+    expect(container.textContent).toContain("gateway");
+    expect(container.textContent).not.toContain("Invalid Date");
+  });
 });
diff --git a/ui/src/ui/views/debug.ts b/ui/src/ui/views/debug.ts
index ac1946960f0..51b9cc9d4e2 100644
--- a/ui/src/ui/views/debug.ts
+++ b/ui/src/ui/views/debug.ts
@@ -1,6 +1,7 @@
 import { html, nothing } from "lit";
 import { t } from "../../i18n/index.ts";
 import type { EventLogEntry } from "../app-events.ts";
+import { formatTimeMs } from "../format.ts";
 import { formatEventPayload } from "../presenter.ts";
 
 export type DebugProps = {
@@ -136,7 +137,7 @@ ${JSON.stringify(props.models ?? [], null, 2)}</pre
                   <div class="list-item debug-event-log__item">
                     <div class="list-main">
                       <div class="list-title">${evt.event}</div>
-                      <div class="list-sub">${new Date(evt.ts).toLocaleTimeString()}</div>
+                      <div class="list-sub">${formatTimeMs(evt.ts, undefined, "")}</div>
                     </div>
                     <div class="list-meta debug-event-log__meta">
                       <pre class="code-block debug-event-log__payload">