diff --git a/src/proxy/upstream-url.ts b/src/proxy/upstream-url.ts
index d41d89b6..5b81b53d 100644
--- a/src/proxy/upstream-url.ts
+++ b/src/proxy/upstream-url.ts
@@ -9,6 +9,11 @@ function ensureSupportedProtocol(parsed: URL): void {
   }
 }
 
+function isOpenRouterHost(hostname: string): boolean {
+  const normalized = hostname.toLowerCase();
+  return normalized === 'openrouter.ai' || normalized.endsWith('.openrouter.ai');
+}
+
 function buildResolvedUrl(baseUrl: string, suffix: string): string {
   const parsed = new URL(baseUrl);
   ensureSupportedProtocol(parsed);
@@ -18,6 +23,11 @@ function buildResolvedUrl(baseUrl: string, suffix: string): string {
     return parsed.toString();
   }
 
+  if (isOpenRouterHost(parsed.hostname) && pathname.endsWith('/api')) {
+    parsed.pathname = `${pathname}/v1${suffix}`;
+    return parsed.toString();
+  }
+
   if (pathname.endsWith('/v1') || pathname.endsWith('/api')) {
     parsed.pathname = `${pathname}${suffix.startsWith('/') ? suffix : `/${suffix}`}`;
     return parsed.toString();
diff --git a/src/shared/provider-preset-catalog.ts b/src/shared/provider-preset-catalog.ts
index b94fe6e8..5d934789 100644
--- a/src/shared/provider-preset-catalog.ts
+++ b/src/shared/provider-preset-catalog.ts
@@ -49,7 +49,7 @@ export interface ProviderPresetDefinition {
   icon?: string;
 }
 
-export const OPENROUTER_BASE_URL = 'https://openrouter.ai/api';
+export const OPENROUTER_BASE_URL = 'https://openrouter.ai/api/v1';
 
 /**
  * Legacy aliases mapped to canonical preset IDs.
diff --git a/tests/unit/api/profile-writer-anthropic.test.ts b/tests/unit/api/profile-writer-anthropic.test.ts
index 0416c321..5a497d98 100644
--- a/tests/unit/api/profile-writer-anthropic.test.ts
+++ b/tests/unit/api/profile-writer-anthropic.test.ts
@@ -134,7 +134,7 @@ describe('profile-writer Anthropic direct', () => {
   it('preserves OpenRouter ANTHROPIC_API_KEY blank behavior', () => {
     const result = createApiProfile(
       'openrouter-test',
-      'https://openrouter.ai/api',
+      'https://openrouter.ai/api/v1',
       'sk-or-testkey',
       { default: 'anthropic/claude-opus-4.5', opus: 'anthropic/claude-opus-4.5', sonnet: 'anthropic/claude-opus-4.5', haiku: 'anthropic/claude-opus-4.5' }
     );
@@ -145,7 +145,7 @@ describe('profile-writer Anthropic direct', () => {
     const settings = JSON.parse(fs.readFileSync(settingsPath, 'utf8'));
 
     // OpenRouter: proxy mode with ANTHROPIC_API_KEY explicitly blank
-    expect(settings.env.ANTHROPIC_BASE_URL).toBe('https://openrouter.ai/api');
+    expect(settings.env.ANTHROPIC_BASE_URL).toBe('https://openrouter.ai/api/v1');
     expect(settings.env.ANTHROPIC_AUTH_TOKEN).toBe('sk-or-testkey');
     expect(settings.env.ANTHROPIC_API_KEY).toBe('');
   });
diff --git a/tests/unit/api/provider-presets.test.ts b/tests/unit/api/provider-presets.test.ts
index e672b496..8d2dc167 100644
--- a/tests/unit/api/provider-presets.test.ts
+++ b/tests/unit/api/provider-presets.test.ts
@@ -92,6 +92,11 @@ describe('provider-presets', () => {
     expect(isValidPresetId('hf')).toBe(true);
   });
 
+  it('uses OpenRouter v1 as the OpenAI-compatible API root', () => {
+    const preset = getPresetById('openrouter');
+    expect(preset?.baseUrl).toBe('https://openrouter.ai/api/v1');
+  });
+
   it('keeps Anthropic direct last in the recommended preset order and reuses the Claude logo', () => {
     const recommendedPresetIds = PROVIDER_PRESETS.filter(
       (preset) => preset.category === 'recommended'
diff --git a/tests/unit/proxy/upstream-url.test.ts b/tests/unit/proxy/upstream-url.test.ts
new file mode 100644
index 00000000..4776ea87
--- /dev/null
+++ b/tests/unit/proxy/upstream-url.test.ts
@@ -0,0 +1,31 @@
+import { describe, expect, it } from 'bun:test';
+import {
+  resolveOpenAIChatCompletionsUrl,
+  resolveOpenAIModelsUrl,
+} from '../../../src/proxy/upstream-url';
+
+describe('OpenAI-compatible upstream URL resolution', () => {
+  it('routes current OpenRouter API roots through /api/v1', () => {
+    expect(resolveOpenAIChatCompletionsUrl('https://openrouter.ai/api/v1')).toBe(
+      'https://openrouter.ai/api/v1/chat/completions'
+    );
+    expect(resolveOpenAIModelsUrl('https://openrouter.ai/api/v1')).toBe(
+      'https://openrouter.ai/api/v1/models'
+    );
+  });
+
+  it('repairs legacy OpenRouter /api roots before appending OpenAI endpoints', () => {
+    expect(resolveOpenAIChatCompletionsUrl('https://openrouter.ai/api')).toBe(
+      'https://openrouter.ai/api/v1/chat/completions'
+    );
+    expect(resolveOpenAIModelsUrl('https://openrouter.ai/api')).toBe(
+      'https://openrouter.ai/api/v1/models'
+    );
+  });
+
+  it('does not rewrite non-OpenRouter /api roots', () => {
+    expect(resolveOpenAIChatCompletionsUrl('https://example.test/api')).toBe(
+      'https://example.test/api/chat/completions'
+    );
+  });
+});