diff --git a/readme.md b/readme.md
index 9826868a..dd4257fe 100644
--- a/readme.md
+++ b/readme.md
@@ -149,7 +149,7 @@ Returns a [`Response` object](https://developer.mozilla.org/en-US/docs/Web/API/R
 
 Sets `options.method` to the method name and makes a request.
 
-When using a [`Request`](https://developer.mozilla.org/en-US/docs/Web/API/Request) instance as `input`, any URL altering options (such as `prefixUrl`) will be ignored.
+When using a [`Request`](https://developer.mozilla.org/en-US/docs/Web/API/Request) instance as `input`, any URL altering options (such as `startPath`) will be ignored.
 
 #### options
 
@@ -181,7 +181,7 @@ Search parameters to include in the request URL. Setting this will override all
 
 Accepts any value supported by [`URLSearchParams()`](https://developer.mozilla.org/en-US/docs/Web/API/URLSearchParams/URLSearchParams).
 
-##### prefixUrl
+##### startPath
 
 Type: `string | URL`
 
@@ -194,16 +194,16 @@ import ky from 'ky';
 
 // On https://example.com
 
-const response = await ky('unicorn', {prefixUrl: '/api'});
+const response = await ky('unicorn', {startPath: '/api'});
 //=> 'https://example.com/api/unicorn'
 
-const response2 = await ky('unicorn', {prefixUrl: 'https://cats.com'});
+const response2 = await ky('unicorn', {startPath: 'https://cats.com'});
 //=> 'https://cats.com/unicorn'
 ```
 
 Notes:
- - After `prefixUrl` and `input` are joined, the result is resolved against the [base URL](https://developer.mozilla.org/en-US/docs/Web/API/Node/baseURI) of the page (if any).
- - Leading slashes in `input` are disallowed when using this option to enforce consistency and avoid confusion about how the `input` URL is handled, given that `input` will not follow the normal URL resolution rules when `prefixUrl` is being used, which changes the meaning of a leading slash.
+ - After `startPath` and `input` are joined, the result is resolved against the [base URL](https://developer.mozilla.org/en-US/docs/Web/API/Node/baseURI) of the page (if any).
+ - Leading slashes in `input` are disallowed when using this option to enforce consistency and avoid confusion about how the `input` URL is handled, given that `input` will not follow the normal URL resolution rules when `startPath` is being used, which changes the meaning of a leading slash.
 
 ##### retry
 
@@ -519,12 +519,12 @@ import ky from 'ky';
 
 // On https://my-site.com
 
-const api = ky.create({prefixUrl: 'https://example.com/api'});
+const api = ky.create({startPath: 'https://example.com/api'});
 
 const response = await api.get('users/123');
 //=> 'https://example.com/api/users/123'
 
-const response = await api.get('/status', {prefixUrl: ''});
+const response = await api.get('/status', {startPath: ''});
 //=> 'https://my-site.com/status'
 ```
 
diff --git a/source/core/Ky.ts b/source/core/Ky.ts
index 5d64cb80..a1a01151 100644
--- a/source/core/Ky.ts
+++ b/source/core/Ky.ts
@@ -1,7 +1,9 @@
 import {HTTPError} from '../errors/HTTPError.js';
 import {TimeoutError} from '../errors/TimeoutError.js';
 import type {Hooks} from '../types/hooks.js';
-import type {Input, InternalOptions, NormalizedOptions, Options, SearchParamsInit} from '../types/options.js';
+import type {
+	Input, InternalOptions, NormalizedOptions, Options, SearchParamsInit,
+} from '../types/options.js';
 import {type ResponsePromise} from '../types/ResponsePromise.js';
 import {deepMerge, mergeHeaders} from '../utils/merge.js';
 import {normalizeRequestMethod, normalizeRetryOptions} from '../utils/normalize.js';
@@ -137,9 +139,9 @@ export class Ky {
 				options.hooks,
 			),
 			method: normalizeRequestMethod(options.method ?? (this._input as Request).method),
-			// eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
-			prefixUrl: String(options.prefixUrl || ''),
 			retry: normalizeRetryOptions(options.retry),
+			// eslint-disable-next-line @typescript-eslint/prefer-nullish-coalescing
+			startPath: String(options.startPath || ''),
 			throwHttpErrors: options.throwHttpErrors !== false,
 			timeout: options.timeout ?? 10_000,
 			fetch: options.fetch ?? globalThis.fetch.bind(globalThis),
@@ -149,16 +151,22 @@ export class Ky {
 			throw new TypeError('`input` must be a string, URL, or Request');
 		}
 
-		if (this._options.prefixUrl && typeof this._input === 'string') {
-			if (this._input.startsWith('/')) {
-				throw new Error('`input` must not begin with a slash when using `prefixUrl`');
-			}
+		if (typeof this._input === 'string') {
+			if (this._options.startPath) {
+				if (!this._options.startPath.endsWith('/')) {
+					this._options.startPath += '/';
+				}
 
-			if (!this._options.prefixUrl.endsWith('/')) {
-				this._options.prefixUrl += '/';
+				if (this._input.startsWith('/')) {
+					this._input = this._input.slice(1);
+				}
+
+				this._input = this._options.startPath + this._input;
 			}
 
-			this._input = this._options.prefixUrl + this._input;
+			if (this._options.baseUrl) {
+				this._input = new URL(this._input, (new Request(options.baseUrl)).url);
+			}
 		}
 
 		if (supportsAbortController) {
diff --git a/source/core/constants.ts b/source/core/constants.ts
index 86055489..c4f559fb 100644
--- a/source/core/constants.ts
+++ b/source/core/constants.ts
@@ -61,7 +61,7 @@ export const kyOptionKeys: KyOptionsRegistry = {
 	parseJson: true,
 	stringifyJson: true,
 	searchParams: true,
-	prefixUrl: true,
+	startPath: true,
 	retry: true,
 	timeout: true,
 	hooks: true,
diff --git a/source/types/options.ts b/source/types/options.ts
index 22fd0651..a7a4e54d 100644
--- a/source/types/options.ts
+++ b/source/types/options.ts
@@ -97,8 +97,8 @@ export type KyOptions = {
 	Useful when used with [`ky.extend()`](#kyextenddefaultoptions) to create niche-specific Ky-instances.
 
 	Notes:
-	 - After `prefixUrl` and `input` are joined, the result is resolved against the [base URL](https://developer.mozilla.org/en-US/docs/Web/API/Node/baseURI) of the page (if any).
-	 - Leading slashes in `input` are disallowed when using this option to enforce consistency and avoid confusion about how the `input` URL is handled, given that `input` will not follow the normal URL resolution rules when `prefixUrl` is being used, which changes the meaning of a leading slash.
+	 - After `startPath` and `input` are joined, the result is resolved against the [base URL](https://developer.mozilla.org/en-US/docs/Web/API/Node/baseURI) of the page (if any).
+	 - Leading slashes in `input` are disallowed when using this option to enforce consistency and avoid confusion about how the `input` URL is handled, given that `input` will not follow the normal URL resolution rules when `startPath` is being used, which changes the meaning of a leading slash.
 
 	@example
 	```
@@ -106,14 +106,14 @@ export type KyOptions = {
 
 	// On https://example.com
 
-	const response = await ky('unicorn', {prefixUrl: '/api'});
+	const response = await ky('unicorn', {startPath: '/api'});
 	//=> 'https://example.com/api/unicorn'
 
-	const response = await ky('unicorn', {prefixUrl: 'https://cats.com'});
+	const response = await ky('unicorn', {startPath: 'https://cats.com'});
 	//=> 'https://cats.com/unicorn'
 	```
 	*/
-	prefixUrl?: URL | string;
+	startPath?: URL | string;
 
 	/**
 	An object representing `limit`, `methods`, `statusCodes` and `maxRetryAfter` fields for maximum retry count, allowed methods, allowed status codes and maximum [`Retry-After`](https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Retry-After) time.
@@ -265,12 +265,12 @@ export interface Options extends KyOptions, Omit<RequestInit, 'headers'> { // es
 
 export type InternalOptions = Required<
 Omit<Options, 'hooks' | 'retry'>,
-'fetch' | 'prefixUrl' | 'timeout'
+'fetch' | 'startPath' | 'timeout'
 > & {
 	headers: Required<Headers>;
 	hooks: Required<Hooks>;
 	retry: Required<RetryOptions>;
-	prefixUrl: string;
+	startPath: string;
 };
 
 /**
@@ -283,7 +283,7 @@ export interface NormalizedOptions extends RequestInit { // eslint-disable-line
 
 	// Extended from custom `KyOptions`, but ensured to be set (not optional).
 	retry: RetryOptions;
-	prefixUrl: string;
+	startPath: string;
 	onDownloadProgress: Options['onDownloadProgress'];
 }
 
diff --git a/test/base-url.ts b/test/base-url.ts
new file mode 100644
index 00000000..4a614d22
--- /dev/null
+++ b/test/base-url.ts
@@ -0,0 +1,39 @@
+import test from 'ava';
+import ky from '../source/index.js';
+import {createHttpTestServer} from './helpers/create-http-test-server.js';
+
+test('baseUrl option', async t => {
+	const server = await createHttpTestServer();
+	server.get('/', (_request, response) => {
+		response.end('/');
+	});
+	server.get('/foo', (_request, response) => {
+		response.end('/foo');
+	});
+	server.get('/bar', (_request, response) => {
+		response.end('/bar');
+	});
+	server.get('/foo/bar', (_request, response) => {
+		response.end('/foo/bar');
+	});
+
+	t.is(
+		// @ts-expect-error {baseUrl: boolean} isn't officially supported
+		await ky(`${server.url}/foo/bar`, {baseUrl: false}).text(),
+		'/foo/bar',
+	);
+	t.is(await ky(`${server.url}/foo/bar`, {baseUrl: ''}).text(), '/foo/bar');
+	t.is(await ky(new URL(`${server.url}/foo/bar`), {baseUrl: ''}).text(), '/foo/bar');
+	t.is(await ky('foo/bar', {baseUrl: server.url}).text(), '/foo/bar');
+	t.is(await ky('foo/bar', {baseUrl: new URL(server.url)}).text(), '/foo/bar');
+	t.is(await ky('/bar', {baseUrl: `${server.url}/foo/`}).text(), '/bar');
+	t.is(await ky('/bar', {baseUrl: `${server.url}/foo`}).text(), '/bar');
+	t.is(await ky('bar', {baseUrl: `${server.url}/foo/`}).text(), '/foo/bar');
+	t.is(await ky('bar', {baseUrl: `${server.url}/foo`}).text(), '/bar');
+	t.is(await ky('bar', {baseUrl: new URL(`${server.url}/foo`)}).text(), '/bar');
+	t.is(await ky('', {baseUrl: server.url}).text(), '/');
+	t.is(await ky('', {baseUrl: `${server.url}/`}).text(), '/');
+	t.is(await ky('', {baseUrl: new URL(server.url)}).text(), '/');
+
+	await server.close();
+});
diff --git a/test/browser.ts b/test/browser.ts
index 088a0b56..e7da2a75 100644
--- a/test/browser.ts
+++ b/test/browser.ts
@@ -47,7 +47,7 @@ test.afterEach(async () => {
 	await server.close();
 });
 
-defaultBrowsersTest('prefixUrl option', async (t: ExecutionContext, page: Page) => {
+defaultBrowsersTest('startPath option', async (t: ExecutionContext, page: Page) => {
 	server.get('/', (_request, response) => {
 		response.end('zebra');
 	});
@@ -60,16 +60,16 @@ defaultBrowsersTest('prefixUrl option', async (t: ExecutionContext, page: Page)
 	await addKyScriptToPage(page);
 
 	await t.throwsAsync(
-		page.evaluate(async () => window.ky('/foo', {prefixUrl: '/'})),
-		{message: /`input` must not begin with a slash when using `prefixUrl`/},
+		page.evaluate(async () => window.ky('/foo', {startPath: '/'})),
+		{message: /`input` must not begin with a slash when using `startPath`/},
 	);
 
 	const results = await page.evaluate(async (url: string) => Promise.all([
 		window.ky(`${url}/api/unicorn`).text(),
-		// @ts-expect-error unsupported {prefixUrl: null} type
-		window.ky(`${url}/api/unicorn`, {prefixUrl: null}).text(),
-		window.ky('api/unicorn', {prefixUrl: url}).text(),
-		window.ky('api/unicorn', {prefixUrl: `${url}/`}).text(),
+		// @ts-expect-error unsupported {startPath: null} type
+		window.ky(`${url}/api/unicorn`, {startPath: null}).text(),
+		window.ky('api/unicorn', {startPath: url}).text(),
+		window.ky('api/unicorn', {startPath: `${url}/`}).text(),
 	]), server.url);
 
 	t.deepEqual(results, ['rainbow', 'rainbow', 'rainbow', 'rainbow']);
diff --git a/test/fetch.ts b/test/fetch.ts
index 05712087..5f89de69 100644
--- a/test/fetch.ts
+++ b/test/fetch.ts
@@ -43,7 +43,7 @@ test('fetch option takes a custom fetch function', async t => {
 		}).text(),
 		`${fixture}?new#hash`,
 	);
-	t.is(await ky('unicorn', {fetch: customFetch, prefixUrl: `${fixture}/api/`}).text(), `${fixture}/api/unicorn`);
+	t.is(await ky('unicorn', {fetch: customFetch, startPath: `${fixture}/api/`}).text(), `${fixture}/api/unicorn`);
 });
 
 test('options are correctly passed to Fetch #1', async t => {
diff --git a/test/prefix-url.ts b/test/prefix-url.ts
deleted file mode 100644
index e09650b4..00000000
--- a/test/prefix-url.ts
+++ /dev/null
@@ -1,40 +0,0 @@
-import test from 'ava';
-import ky from '../source/index.js';
-import {createHttpTestServer} from './helpers/create-http-test-server.js';
-
-test('prefixUrl option', async t => {
-	const server = await createHttpTestServer();
-	server.get('/', (_request, response) => {
-		response.end('zebra');
-	});
-	server.get('/api/unicorn', (_request, response) => {
-		response.end('rainbow');
-	});
-
-	t.is(
-		// @ts-expect-error {prefixUrl: boolean} isn't officially supported
-		await ky(`${server.url}/api/unicorn`, {prefixUrl: false}).text(),
-		'rainbow',
-	);
-	t.is(await ky(`${server.url}/api/unicorn`, {prefixUrl: ''}).text(), 'rainbow');
-	t.is(await ky(new URL(`${server.url}/api/unicorn`), {prefixUrl: ''}).text(), 'rainbow');
-	t.is(await ky('api/unicorn', {prefixUrl: server.url}).text(), 'rainbow');
-	t.is(await ky('api/unicorn', {prefixUrl: new URL(server.url)}).text(), 'rainbow');
-	t.is(await ky('unicorn', {prefixUrl: `${server.url}/api`}).text(), 'rainbow');
-	t.is(await ky('unicorn', {prefixUrl: `${server.url}/api/`}).text(), 'rainbow');
-	t.is(await ky('unicorn', {prefixUrl: new URL(`${server.url}/api`)}).text(), 'rainbow');
-	t.is(await ky('', {prefixUrl: server.url}).text(), 'zebra');
-	t.is(await ky('', {prefixUrl: `${server.url}/`}).text(), 'zebra');
-	t.is(await ky('', {prefixUrl: new URL(server.url)}).text(), 'zebra');
-
-	t.throws(
-		() => {
-			void ky('/unicorn', {prefixUrl: `${server.url}/api`});
-		},
-		{
-			message: '`input` must not begin with a slash when using `prefixUrl`',
-		},
-	);
-
-	await server.close();
-});
diff --git a/test/start-path.ts b/test/start-path.ts
new file mode 100644
index 00000000..424306e2
--- /dev/null
+++ b/test/start-path.ts
@@ -0,0 +1,39 @@
+import test from 'ava';
+import ky from '../source/index.js';
+import {createHttpTestServer} from './helpers/create-http-test-server.js';
+
+test('startPath option', async t => {
+	const server = await createHttpTestServer();
+	server.get('/', (_request, response) => {
+		response.end('/');
+	});
+	server.get('/foo', (_request, response) => {
+		response.end('/foo');
+	});
+	server.get('/bar', (_request, response) => {
+		response.end('/bar');
+	});
+	server.get('/foo/bar', (_request, response) => {
+		response.end('/foo/bar');
+	});
+
+	t.is(
+		// @ts-expect-error {startPath: boolean} isn't officially supported
+		await ky(`${server.url}/foo/bar`, {startPath: false}).text(),
+		'/foo/bar',
+	);
+	t.is(await ky(`${server.url}/foo/bar`, {startPath: ''}).text(), '/foo/bar');
+	t.is(await ky(new URL(`${server.url}/foo/bar`), {startPath: ''}).text(), '/foo/bar');
+	t.is(await ky('foo/bar', {startPath: server.url}).text(), '/foo/bar');
+	t.is(await ky('foo/bar', {startPath: new URL(server.url)}).text(), '/foo/bar');
+	t.is(await ky('/bar', {startPath: `${server.url}/foo/`}).text(), '/foo/bar');
+	t.is(await ky('/bar', {startPath: `${server.url}/foo`}).text(), '/foo/bar');
+	t.is(await ky('bar', {startPath: `${server.url}/foo/`}).text(), '/foo/bar');
+	t.is(await ky('bar', {startPath: `${server.url}/foo`}).text(), '/foo/bar');
+	t.is(await ky('bar', {startPath: new URL(`${server.url}/foo`)}).text(), '/foo/bar');
+	t.is(await ky('', {startPath: server.url}).text(), '/');
+	t.is(await ky('', {startPath: `${server.url}/`}).text(), '/');
+	t.is(await ky('', {startPath: new URL(server.url)}).text(), '/');
+
+	await server.close();
+});