diff --git a/src/commands/config-image-analysis-command.ts b/src/commands/config-image-analysis-command.ts
index 0301cfc6..ba9f855d 100644
--- a/src/commands/config-image-analysis-command.ts
+++ b/src/commands/config-image-analysis-command.ts
@@ -40,6 +40,13 @@ const IMAGE_ANALYSIS_PROVIDER_ALIASES = Object.freeze(
   )
 );
 
+function isConfiguredImageAnalysisBackend(
+  backend: string | null,
+  providerModels: Record<string, string>
+): backend is string {
+  return Boolean(backend && Object.prototype.hasOwnProperty.call(providerModels, backend));
+}
+
 function parseArgs(args: string[]): ImageAnalysisCommandOptions {
   const options: ImageAnalysisCommandOptions = {
     enable: hasAnyFlag(args, ['--enable']),
@@ -296,7 +303,7 @@ export async function handleConfigImageAnalysisCommand(args: string[]): Promise<
       options.setFallback,
       Object.keys(imageConfig.provider_models)
     );
-    if (!normalizedBackend) {
+    if (!isConfiguredImageAnalysisBackend(normalizedBackend, imageConfig.provider_models)) {
       console.error(fail(`Invalid fallback backend: ${options.setFallback}`));
       process.exit(1);
     }
@@ -314,7 +321,7 @@ export async function handleConfigImageAnalysisCommand(args: string[]): Promise<
       console.error(fail('Profile name cannot be empty'));
       process.exit(1);
     }
-    if (!normalizedBackend) {
+    if (!isConfiguredImageAnalysisBackend(normalizedBackend, imageConfig.provider_models)) {
       console.error(fail(`Invalid backend: ${options.setProfileBackend.backend}`));
       process.exit(1);
     }
diff --git a/tests/unit/commands/config-image-analysis-command.test.ts b/tests/unit/commands/config-image-analysis-command.test.ts
index 6a7f9134..3215964e 100644
--- a/tests/unit/commands/config-image-analysis-command.test.ts
+++ b/tests/unit/commands/config-image-analysis-command.test.ts
@@ -4,7 +4,7 @@
  * Unit tests for ccs config image-analysis subcommand.
  */
 
-import { describe, it, expect, beforeEach, afterEach, spyOn, mock } from 'bun:test';
+import { describe, it, expect, beforeEach, afterEach } from 'bun:test';
 import * as fs from 'fs';
 import * as path from 'path';
 import * as os from 'os';
@@ -33,6 +33,13 @@ function createConfigYaml(content: string): void {
   fs.writeFileSync(path.join(testDir, 'config.yaml'), content, 'utf8');
 }
 
+async function loadHandleConfigImageAnalysisCommand() {
+  const mod = await import(
+    `../../../src/commands/config-image-analysis-command?test=${Date.now()}-${Math.random()}`
+  );
+  return mod.handleConfigImageAnalysisCommand;
+}
+
 describe('config image-analysis command', () => {
   describe('config file parsing', () => {
     it('should parse enabled status from config.yaml', () => {
@@ -152,6 +159,56 @@ image_analysis:
         expect(validProviders.includes(provider)).toBe(false);
       }
     });
+
+    it('rejects invalid fallback backends that are not configured', async () => {
+      const handleConfigImageAnalysisCommand = await loadHandleConfigImageAnalysisCommand();
+      const originalProcessExit = process.exit;
+
+      process.exit = ((code?: number) => {
+        throw new Error(`process.exit(${code ?? 0})`);
+      }) as typeof process.exit;
+
+      try {
+        await expect(
+          handleConfigImageAnalysisCommand(['--set-fallback', 'unknown-provider'])
+        ).rejects.toThrow('process.exit(1)');
+      } finally {
+        process.exit = originalProcessExit;
+      }
+
+      const configPath = path.join(testDir, 'config.yaml');
+      if (fs.existsSync(configPath)) {
+        const content = fs.readFileSync(configPath, 'utf8');
+        expect(content).not.toContain('fallback_backend: unknown-provider');
+      } else {
+        expect(fs.existsSync(configPath)).toBe(false);
+      }
+    });
+
+    it('rejects invalid profile backend mappings that are not configured', async () => {
+      const handleConfigImageAnalysisCommand = await loadHandleConfigImageAnalysisCommand();
+      const originalProcessExit = process.exit;
+
+      process.exit = ((code?: number) => {
+        throw new Error(`process.exit(${code ?? 0})`);
+      }) as typeof process.exit;
+
+      try {
+        await expect(
+          handleConfigImageAnalysisCommand(['--set-profile-backend', 'orq', 'unknown-provider'])
+        ).rejects.toThrow('process.exit(1)');
+      } finally {
+        process.exit = originalProcessExit;
+      }
+
+      const configPath = path.join(testDir, 'config.yaml');
+      if (fs.existsSync(configPath)) {
+        const content = fs.readFileSync(configPath, 'utf8');
+        expect(content).not.toContain('unknown-provider');
+      } else {
+        expect(fs.existsSync(configPath)).toBe(false);
+      }
+    });
   });
 
   describe('default configuration', () => {