diff --git a/CHANGELOG.md b/CHANGELOG.md
index 858d235c9..f42adebf8 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -96,6 +96,7 @@ Docs: https://docs.openclaw.ai
 - Slack/HTTP mode startup: treat Slack HTTP accounts as configured when `botToken` + `signingSecret` are present (without requiring `appToken`) in channel config/runtime status so webhook mode is not silently skipped. (#30567)
 - Slack/Usage footer formatting: wrap session keys in inline code in full response-usage footers so Slack does not parse colon-delimited session segments as emoji shortcodes. (#30258) Thanks @pushkarsingh32.
 - Slack/Socket Mode slash startup: treat `app.options()` registration as best-effort and fall back to static arg menus when listener registration fails, preventing Slack monitor startup crash loops on receiver init edge cases. (#21715)
+- Slack/Legacy streaming config: map boolean `channels.slack.streaming=false` to unified streaming mode `off` (with `nativeStreaming=false`) so legacy configs correctly disable draft preview/native streaming instead of defaulting to `partial`. (#25990) Thanks @chilu18.
 - Onboarding/Custom providers: raise default custom-provider model context window to the runtime hard minimum (16k) and auto-heal existing custom model entries below that threshold during reconfiguration, preventing immediate `Model context window too small (4096 tokens)` failures. (#21653) Thanks @r4jiv007.
 - Web UI/Assistant text: strip internal `<relevant-memories>...</relevant-memories>` scaffolding from rendered assistant messages (while preserving code-fence literals), preventing memory-context leakage in chat output for models that echo internal blocks. (#29851) Thanks @Valkster70.
 - Dashboard/Sessions: allow authenticated Control UI clients to delete and patch sessions while still blocking regular webchat clients from session mutation RPCs, fixing Dashboard session delete failures. (#21264) Thanks @jskoiz.
diff --git a/src/commands/doctor-legacy-config.test.ts b/src/commands/doctor-legacy-config.test.ts
index acc256c13..89bc93bbc 100644
--- a/src/commands/doctor-legacy-config.test.ts
+++ b/src/commands/doctor-legacy-config.test.ts
@@ -31,4 +31,21 @@ describe("normalizeCompatibilityConfigValues preview streaming aliases", () => {
       "Normalized channels.discord.streaming boolean → enum (partial).",
     ]);
   });
+
+  it("normalizes slack boolean streaming aliases to enum and native streaming", () => {
+    const res = normalizeCompatibilityConfigValues({
+      channels: {
+        slack: {
+          streaming: false,
+        },
+      },
+    });
+
+    expect(res.config.channels?.slack?.streaming).toBe("off");
+    expect(res.config.channels?.slack?.nativeStreaming).toBe(false);
+    expect(res.config.channels?.slack?.streamMode).toBeUndefined();
+    expect(res.changes).toEqual([
+      "Moved channels.slack.streaming (boolean) → channels.slack.nativeStreaming (false).",
+    ]);
+  });
 });
diff --git a/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts b/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
index 5682fce27..45f51e6a2 100644
--- a/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
+++ b/src/config/config.legacy-config-detection.rejects-routing-allowfrom.test.ts
@@ -597,7 +597,7 @@ describe("legacy config detection", () => {
           },
         },
         assert: (config: NonNullable<OpenClawConfig>) => {
-          expect(config.channels?.slack?.streaming).toBe("partial");
+          expect(config.channels?.slack?.streaming).toBe("off");
           expect(config.channels?.slack?.nativeStreaming).toBe(false);
         },
       },
diff --git a/src/config/discord-preview-streaming.ts b/src/config/discord-preview-streaming.ts
index 684c5eff1..5b93b1ccb 100644
--- a/src/config/discord-preview-streaming.ts
+++ b/src/config/discord-preview-streaming.ts
@@ -121,9 +121,9 @@ export function resolveSlackStreamingMode(
   if (legacyStreamMode) {
     return mapSlackLegacyDraftStreamModeToStreaming(legacyStreamMode);
   }
-  // Legacy `streaming` was a Slack native-streaming toggle; preview mode stayed replace.
+  // Legacy boolean `streaming` values map to the unified enum.
   if (typeof params.streaming === "boolean") {
-    return "partial";
+    return params.streaming ? "partial" : "off";
   }
   return "partial";
 }
diff --git a/src/slack/stream-mode.test.ts b/src/slack/stream-mode.test.ts
index c0146d323..fdbeb70ed 100644
--- a/src/slack/stream-mode.test.ts
+++ b/src/slack/stream-mode.test.ts
@@ -40,12 +40,17 @@ describe("resolveSlackStreamingConfig", () => {
     });
   });
 
-  it("moves legacy streaming boolean to native streaming toggle", () => {
+  it("maps legacy streaming booleans to unified mode and native streaming toggle", () => {
     expect(resolveSlackStreamingConfig({ streaming: false })).toEqual({
-      mode: "partial",
+      mode: "off",
       nativeStreaming: false,
       draftMode: "replace",
     });
+    expect(resolveSlackStreamingConfig({ streaming: true })).toEqual({
+      mode: "partial",
+      nativeStreaming: true,
+      draftMode: "replace",
+    });
   });
 
   it("accepts unified enum values directly", () => {