diff --git a/src/slack/monitor/message-handler/dispatch.ts b/src/slack/monitor/message-handler/dispatch.ts
index 8e3db47d5e6..2022100ce19 100644
--- a/src/slack/monitor/message-handler/dispatch.ts
+++ b/src/slack/monitor/message-handler/dispatch.ts
@@ -12,6 +12,7 @@ import { danger, logVerbose, shouldLogVerbose } from "../../../globals.js";
 import { resolveAgentOutboundIdentity } from "../../../infra/outbound/identity.js";
 import { removeSlackReaction } from "../../actions.js";
 import { createSlackDraftStream } from "../../draft-stream.js";
+import { markdownToSlackMrkdwn } from "../../format.js";
 import { recordSlackThreadParticipation } from "../../sent-thread-cache.js";
 import {
   applyAppendOnlyStreamUpdate,
@@ -290,7 +291,7 @@ export async function dispatchPreparedSlackMessage(prepared: PreparedSlackMessag
             token: ctx.botToken,
             channel: draftChannelId,
             ts: draftMessageId,
-            text: finalText.trim(),
+            text: markdownToSlackMrkdwn(finalText.trim()),
           });
           return;
         } catch (err) {
diff --git a/src/slack/streaming.ts b/src/slack/streaming.ts
index 936fba79feb..d2ed0e02612 100644
--- a/src/slack/streaming.ts
+++ b/src/slack/streaming.ts
@@ -14,6 +14,7 @@
 import type { WebClient } from "@slack/web-api";
 import type { ChatStreamer } from "@slack/web-api/dist/chat-stream.js";
 import { logVerbose } from "../globals.js";
+import { markdownToSlackMrkdwn } from "./format.js";
 
 // ---------------------------------------------------------------------------
 // Types
@@ -99,7 +100,7 @@ export async function startSlackStream(
   // If initial text is provided, send it as the first append which will
   // trigger the ChatStreamer to call chat.startStream under the hood.
   if (text) {
-    await streamer.append({ markdown_text: text });
+    await streamer.append({ markdown_text: markdownToSlackMrkdwn(text) });
     logVerbose(`slack-stream: appended initial text (${text.length} chars)`);
   }
 
@@ -121,7 +122,7 @@ export async function appendSlackStream(params: AppendSlackStreamParams): Promis
     return;
   }
 
-  await session.streamer.append({ markdown_text: text });
+  await session.streamer.append({ markdown_text: markdownToSlackMrkdwn(text) });
   logVerbose(`slack-stream: appended ${text.length} chars`);
 }
 
@@ -147,7 +148,7 @@ export async function stopSlackStream(params: StopSlackStreamParams): Promise<vo
     }`,
   );
 
-  await session.streamer.stop(text ? { markdown_text: text } : undefined);
+  await session.streamer.stop(text ? { markdown_text: markdownToSlackMrkdwn(text) } : undefined);
 
   logVerbose("slack-stream: stream stopped");
 }