diff --git a/.changeset/nice-pillows-type.md b/.changeset/nice-pillows-type.md
new file mode 100644
index 0000000..9d0045d
--- /dev/null
+++ b/.changeset/nice-pillows-type.md
@@ -0,0 +1,5 @@
+---
+'proxy-agent': minor
+---
+
+Allow `getProxyForUrl()` option to return a Promise
diff --git a/packages/proxy-agent/src/index.ts b/packages/proxy-agent/src/index.ts
index c051f8a..496e185 100644
--- a/packages/proxy-agent/src/index.ts
+++ b/packages/proxy-agent/src/index.ts
@@ -22,7 +22,7 @@ type ValidProtocol = (typeof PROTOCOLS)[number];
 
 type AgentConstructor = new (...args: never[]) => Agent;
 
-type GetProxyForUrlCallback = (url: string) => string;
+type GetProxyForUrlCallback = (url: string) => string | Promise<string>;
 
 /**
  * Supported proxy types.
@@ -115,7 +115,7 @@ export class ProxyAgent extends Agent {
 			: 'http:';
 		const host = req.getHeader('host');
 		const url = new URL(req.path, `${protocol}//${host}`).href;
-		const proxy = this.getProxyForUrl(url);
+		const proxy = await this.getProxyForUrl(url);
 
 		if (!proxy) {
 			debug('Proxy not enabled for URL: %o', url);
diff --git a/packages/proxy-agent/test/test.ts b/packages/proxy-agent/test/test.ts
index 5f6de6e..2544d18 100644
--- a/packages/proxy-agent/test/test.ts
+++ b/packages/proxy-agent/test/test.ts
@@ -2,6 +2,7 @@ import * as fs from 'fs';
 import * as http from 'http';
 import * as https from 'https';
 import { URL } from 'url';
+import { promisify } from 'util';
 import { once } from 'events';
 import assert from 'assert';
 import WebSocket, { WebSocketServer } from 'ws';
@@ -287,6 +288,33 @@ describe('ProxyAgent', () => {
 			assert(gotCall);
 			assert(requestUrl.href === urlParameter);
 		});
+
+		it('should call provided function with asynchronous getProxyForUrl option', async () => {
+			let gotCall = false;
+			let urlParameter = '';
+			httpsServer.once('request', function (req, res) {
+				res.end(JSON.stringify(req.headers));
+			});
+
+			const agent = new ProxyAgent({
+				rejectUnauthorized: false,
+				getProxyForUrl: async(u) => {
+					gotCall = true;
+					urlParameter = u;
+					await promisify(setTimeout)(1);
+					return httpsProxyServerUrl.href;
+				},
+			});
+			const requestUrl = new URL('/test', httpsServerUrl);
+			const res = await req(requestUrl, {
+				agent,
+				rejectUnauthorized: false,
+			});
+			const body = await json(res);
+			assert(httpsServerUrl.host === body.host);
+			assert(gotCall);
+			assert(requestUrl.href === urlParameter);
+		});
 	});
 
 	describe('"ws" module', () => {