diff --git a/README.md b/README.md
index 8dd5c59..11cf99b 100644
--- a/README.md
+++ b/README.md
@@ -59,6 +59,39 @@ Domains automatically match all subdomains:
 sudo awf --allow-domains github.com "curl https://api.github.com"  # ✓ works
 ```
 
+### Using a Domains File
+
+For longer domain lists, use a file (one domain per line):
+
+```bash
+# Create a domains file
+cat > allowed-domains.txt << EOF
+# GitHub domains
+github.com
+api.github.com
+githubusercontent.com
+
+# Other services
+googleapis.com
+arxiv.org
+EOF
+
+# Use the file
+sudo awf --allow-domains-file allowed-domains.txt "curl https://api.github.com"
+
+# Combine both methods
+sudo awf \
+  --allow-domains example.com \
+  --allow-domains-file allowed-domains.txt \
+  "curl https://api.github.com"
+```
+
+**File Format:**
+- One domain per line
+- Lines starting with `#` are treated as comments
+- Empty lines are ignored
+- Whitespace is trimmed from each line
+
 Common domain lists:
 
 ```bash
diff --git a/src/cli.test.ts b/src/cli.test.ts
index c0d3064..2c22233 100644
--- a/src/cli.test.ts
+++ b/src/cli.test.ts
@@ -1,7 +1,10 @@
 import { Command } from 'commander';
-import { parseEnvironmentVariables } from './cli';
+import { parseEnvironmentVariables, parseDomainsFromFile } from './cli';
 import { redactSecrets } from './redact-secrets';
 import { parseDomains } from './cli';
+import * as fs from 'fs';
+import * as path from 'path';
+import * as os from 'os';
 
 describe('cli', () => {
   describe('domain parsing', () => {
@@ -36,6 +39,98 @@ describe('cli', () => {
     });
   });
 
+  describe('domain parsing from file', () => {
+    let tempDir: string;
+    
+    beforeEach(() => {
+      tempDir = fs.mkdtempSync(path.join(os.tmpdir(), 'awf-test-'));
+    });
+
+    afterEach(() => {
+      fs.rmSync(tempDir, { recursive: true, force: true });
+    });
+
+    it('should parse domains from file with one domain per line', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, 'github.com\napi.github.com\nnpmjs.org');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual(['github.com', 'api.github.com', 'npmjs.org']);
+    });
+
+    it('should filter out empty lines', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, 'github.com\n\napi.github.com\n\n\nnpmjs.org\n');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual(['github.com', 'api.github.com', 'npmjs.org']);
+    });
+
+    it('should filter out comment lines starting with #', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, '# This is a comment\ngithub.com\n# Another comment\napi.github.com');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual(['github.com', 'api.github.com']);
+    });
+
+    it('should trim whitespace from each line', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, '  github.com  \n\tapi.github.com\t\n   npmjs.org   ');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual(['github.com', 'api.github.com', 'npmjs.org']);
+    });
+
+    it('should handle file with mixed content', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, 
+        '# GitHub domains\ngithub.com\n  api.github.com  \n\n# NPM registry\nnpmjs.org\n# End of file\n'
+      );
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual(['github.com', 'api.github.com', 'npmjs.org']);
+    });
+
+    it('should handle empty file', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, '');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual([]);
+    });
+
+    it('should handle file with only comments and whitespace', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, '# Comment 1\n\n  \n# Comment 2\n\t\n');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual([]);
+    });
+
+    it('should throw error for non-existent file', () => {
+      const filePath = path.join(tempDir, 'nonexistent.txt');
+      
+      expect(() => parseDomainsFromFile(filePath)).toThrow();
+    });
+
+    it('should handle file with Windows line endings', () => {
+      const filePath = path.join(tempDir, 'domains.txt');
+      fs.writeFileSync(filePath, 'github.com\r\napi.github.com\r\nnpmjs.org\r\n');
+      
+      const result = parseDomainsFromFile(filePath);
+      
+      expect(result).toEqual(['github.com', 'api.github.com', 'npmjs.org']);
+    });
+  });
+
   describe('environment variable parsing', () => {
     it('should parse KEY=VALUE format correctly', () => {
       const envVars = ['GITHUB_TOKEN=abc123', 'API_KEY=xyz789'];
diff --git a/src/cli.ts b/src/cli.ts
index ca949a0..5010dab 100644
--- a/src/cli.ts
+++ b/src/cli.ts
@@ -3,6 +3,7 @@
 import { Command } from 'commander';
 import * as path from 'path';
 import * as os from 'os';
+import * as fs from 'fs';
 import { WrapperConfig, LogLevel } from './types';
 import { logger } from './logger';
 import {
@@ -32,6 +33,20 @@ export function parseDomains(input: string): string[] {
     .filter(d => d.length > 0);
 }
 
+/**
+ * Parses domains from a file, one domain per line
+ * @param filePath - Path to the file containing domains
+ * @returns Array of trimmed domain strings with empty lines and comments filtered out
+ * @throws Error if file cannot be read
+ */
+export function parseDomainsFromFile(filePath: string): string[] {
+  const content = fs.readFileSync(filePath, 'utf-8');
+  return content
+    .split('\n')
+    .map(line => line.trim())
+    .filter(line => line.length > 0 && !line.startsWith('#'));
+}
+
 /**
  * Result of parsing environment variables
  */
@@ -71,10 +86,14 @@ program
   .name('awf')
   .description('Network firewall for agentic workflows with domain whitelisting')
   .version('0.1.0')
-  .requiredOption(
+  .option(
     '--allow-domains <domains>',
     'Comma-separated list of allowed domains (e.g., github.com,api.github.com)'
   )
+  .option(
+    '--allow-domains-file <path>',
+    'Path to file containing allowed domains (one per line)'
+  )
   .option(
     '--log-level <level>',
     'Log level: debug, info, warn, error',
@@ -127,10 +146,31 @@ program
 
     logger.setLevel(logLevel);
 
-    const allowedDomains = parseDomains(options.allowDomains);
+    // Parse domains from both sources
+    let allowedDomains: string[] = [];
+    
+    // Parse from --allow-domains flag if provided
+    if (options.allowDomains) {
+      allowedDomains = parseDomains(options.allowDomains);
+    }
+    
+    // Parse from --allow-domains-file if provided
+    if (options.allowDomainsFile) {
+      try {
+        const domainsFromFile = parseDomainsFromFile(options.allowDomainsFile);
+        allowedDomains = [...allowedDomains, ...domainsFromFile];
+      } catch (error) {
+        logger.error(`Failed to read domains file: ${options.allowDomainsFile}`);
+        logger.error(String(error));
+        process.exit(1);
+      }
+    }
+
+    // Remove duplicates
+    allowedDomains = [...new Set(allowedDomains)];
 
     if (allowedDomains.length === 0) {
-      logger.error('At least one domain must be specified with --allow-domains');
+      logger.error('At least one domain must be specified with --allow-domains or --allow-domains-file');
       process.exit(1);
     }