diff --git a/extensions/slack/src/channel.ts b/extensions/slack/src/channel.ts
index 46084d2dfed..d59c7a393ef 100644
--- a/extensions/slack/src/channel.ts
+++ b/extensions/slack/src/channel.ts
@@ -30,6 +30,7 @@ import {
   normalizeLowercaseStringOrEmpty,
   normalizeOptionalString,
 } from "openclaw/plugin-sdk/string-coerce-runtime";
+import { sanitizeAssistantVisibleText } from "openclaw/plugin-sdk/text-chunking";
 import {
   resolveDefaultSlackAccountId,
   resolveSlackAccount,
@@ -423,6 +424,7 @@ const slackChannelOutbound: ChannelOutboundAdapter = {
   deliveryMode: "direct",
   chunker: null,
   textChunkLimit: SLACK_TEXT_LIMIT,
+  sanitizeText: ({ text }) => sanitizeAssistantVisibleText(text),
   normalizePayload: ({ payload, cfg, accountId }) =>
     isSlackInteractiveRepliesEnabled({ cfg, accountId })
       ? compileSlackInteractiveReplies(payload)
diff --git a/extensions/slack/src/outbound-tool-trace-sanitize.test.ts b/extensions/slack/src/outbound-tool-trace-sanitize.test.ts
new file mode 100644
index 00000000000..681ff785433
--- /dev/null
+++ b/extensions/slack/src/outbound-tool-trace-sanitize.test.ts
@@ -0,0 +1,19 @@
+// Slack outbound must strip assistant internal tool-trace scaffolding, matching
+// the sibling channel fixes tracked under #90684 (Telegram #95774 / Google Chat
+// #95084 / IRC #97214). sanitizeAssistantVisibleText keeps mrkdwn formatting.
+import { describe, expect, it } from "vitest";
+import { slackPlugin } from "./channel.js";
+
+describe("slack outbound sanitizeText", () => {
+  it("strips internal tool-trace banners before outbound delivery", () => {
+    const text = "Done.\n⚠️ 🛠️ `search repos (agent)` failed";
+
+    expect(slackPlugin.outbound?.sanitizeText?.({ text, payload: { text } })).toBe("Done.");
+  });
+
+  it("preserves ordinary assistant prose while sanitizing", () => {
+    const text = "The pipeline has 3 open deals.";
+
+    expect(slackPlugin.outbound?.sanitizeText?.({ text, payload: { text } })).toBe(text);
+  });
+});