diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0b222ef837c..68cbdc6b19b 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -27,6 +27,7 @@ Docs: https://docs.openclaw.ai
 
 ### Fixes
 
+- Providers/OpenRouter: default reasoning to enabled when the selected model advertises `reasoning: true` and no session/directive override is set. (#22513) Thanks @zwffff.
 - Providers/OpenRouter: map `/think` levels to `reasoning.effort` in embedded runs while preserving explicit `reasoning.max_tokens` payloads. (#17236) Thanks @robbyczgw-cla.
 - Gateway/OpenRouter: preserve stored session provider when model IDs are vendor-prefixed (for example, `anthropic/...`) so follow-up turns do not incorrectly route to direct provider APIs. (#22753) Thanks @dndodson.
 - Providers/OpenRouter: preserve the required `openrouter/` prefix for OpenRouter-native model IDs during model-ref normalization. (#12942) Thanks @omair445.
diff --git a/src/agents/model-selection.ts b/src/agents/model-selection.ts
index 2df5acb14ea..6f6773d5c61 100644
--- a/src/agents/model-selection.ts
+++ b/src/agents/model-selection.ts
@@ -529,6 +529,21 @@ export function resolveThinkingDefault(params: {
   return "off";
 }
 
+/** Default reasoning level when session/directive do not set it: "on" if model supports reasoning, else "off". */
+export function resolveReasoningDefault(params: {
+  provider: string;
+  model: string;
+  catalog?: ModelCatalogEntry[];
+}): "on" | "off" {
+  const key = modelKey(params.provider, params.model);
+  const candidate = params.catalog?.find(
+    (entry) =>
+      (entry.provider === params.provider && entry.id === params.model) ||
+      (entry.provider === key && entry.id === params.model),
+  );
+  return candidate?.reasoning === true ? "on" : "off";
+}
+
 /**
  * Resolve the model configured for Gmail hook processing.
  * Returns null if hooks.gmail.model is not set.
diff --git a/src/auto-reply/reply/get-reply-directives.ts b/src/auto-reply/reply/get-reply-directives.ts
index 57d1808d495..f421ed92eae 100644
--- a/src/auto-reply/reply/get-reply-directives.ts
+++ b/src/auto-reply/reply/get-reply-directives.ts
@@ -345,7 +345,7 @@ export async function resolveReplyDirectives(params: {
     directives.verboseLevel ??
     (sessionEntry?.verboseLevel as VerboseLevel | undefined) ??
     (agentCfg?.verboseDefault as VerboseLevel | undefined);
-  const resolvedReasoningLevel: ReasoningLevel =
+  let resolvedReasoningLevel: ReasoningLevel =
     directives.reasoningLevel ??
     (sessionEntry?.reasoningLevel as ReasoningLevel | undefined) ??
     "off";
@@ -389,6 +389,14 @@ export async function resolveReplyDirectives(params: {
   provider = modelState.provider;
   model = modelState.model;
 
+  // When neither directive nor session set reasoning, default to model capability (e.g. OpenRouter with reasoning: true).
+  const reasoningExplicitlySet =
+    directives.reasoningLevel !== undefined ||
+    (sessionEntry?.reasoningLevel !== undefined && sessionEntry?.reasoningLevel !== null);
+  if (!reasoningExplicitlySet && resolvedReasoningLevel === "off") {
+    resolvedReasoningLevel = await modelState.resolveDefaultReasoningLevel();
+  }
+
   let contextTokens = resolveContextTokens({
     agentCfg,
     model,
diff --git a/src/auto-reply/reply/model-selection.test.ts b/src/auto-reply/reply/model-selection.test.ts
index b4f5f3577d4..493adec0515 100644
--- a/src/auto-reply/reply/model-selection.test.ts
+++ b/src/auto-reply/reply/model-selection.test.ts
@@ -264,3 +264,35 @@ describe("createModelSelectionState respects session model override", () => {
     expect(state.model).toBe("deepseek-v3-4bit-mlx");
   });
 });
+
+describe("createModelSelectionState resolveDefaultReasoningLevel", () => {
+  it("returns on when catalog model has reasoning true", async () => {
+    const { loadModelCatalog } = await import("../../agents/model-catalog.js");
+    vi.mocked(loadModelCatalog).mockResolvedValueOnce([
+      { provider: "openrouter", id: "x-ai/grok-4.1-fast", name: "Grok", reasoning: true },
+    ]);
+    const state = await createModelSelectionState({
+      cfg: {} as OpenClawConfig,
+      agentCfg: undefined,
+      defaultProvider: "openrouter",
+      defaultModel: "x-ai/grok-4.1-fast",
+      provider: "openrouter",
+      model: "x-ai/grok-4.1-fast",
+      hasModelDirective: false,
+    });
+    await expect(state.resolveDefaultReasoningLevel()).resolves.toBe("on");
+  });
+
+  it("returns off when catalog model has no reasoning", async () => {
+    const state = await createModelSelectionState({
+      cfg: {} as OpenClawConfig,
+      agentCfg: undefined,
+      defaultProvider: "openai",
+      defaultModel: "gpt-4o-mini",
+      provider: "openai",
+      model: "gpt-4o-mini",
+      hasModelDirective: false,
+    });
+    await expect(state.resolveDefaultReasoningLevel()).resolves.toBe("off");
+  });
+});
diff --git a/src/auto-reply/reply/model-selection.ts b/src/auto-reply/reply/model-selection.ts
index c41abd31b46..1b666b6ded5 100644
--- a/src/auto-reply/reply/model-selection.ts
+++ b/src/auto-reply/reply/model-selection.ts
@@ -8,6 +8,7 @@ import {
   modelKey,
   normalizeProviderId,
   resolveModelRefFromString,
+  resolveReasoningDefault,
   resolveThinkingDefault,
 } from "../../agents/model-selection.js";
 import type { OpenClawConfig } from "../../config/config.js";
@@ -32,6 +33,8 @@ type ModelSelectionState = {
   allowedModelCatalog: ModelCatalog;
   resetModelOverride: boolean;
   resolveDefaultThinkingLevel: () => Promise<ThinkLevel>;
+  /** Default reasoning level from model capability: "on" if model has reasoning, else "off". */
+  resolveDefaultReasoningLevel: () => Promise<"on" | "off">;
   needsModelCatalog: boolean;
 };
 
@@ -397,6 +400,19 @@ export async function createModelSelectionState(params: {
     return defaultThinkingLevel;
   };
 
+  const resolveDefaultReasoningLevel = async (): Promise<"on" | "off"> => {
+    let catalogForReasoning = modelCatalog ?? allowedModelCatalog;
+    if (!catalogForReasoning || catalogForReasoning.length === 0) {
+      modelCatalog = await loadModelCatalog({ config: cfg });
+      catalogForReasoning = modelCatalog;
+    }
+    return resolveReasoningDefault({
+      provider,
+      model,
+      catalog: catalogForReasoning,
+    });
+  };
+
   return {
     provider,
     model,
@@ -404,6 +420,7 @@ export async function createModelSelectionState(params: {
     allowedModelCatalog,
     resetModelOverride,
     resolveDefaultThinkingLevel,
+    resolveDefaultReasoningLevel,
     needsModelCatalog,
   };
 }