diff --git a/.changeset/heavy-yaks-brake.md b/.changeset/heavy-yaks-brake.md
new file mode 100644
index 000000000000..50f2a1f88e3f
--- /dev/null
+++ b/.changeset/heavy-yaks-brake.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/underscore-redirects': minor
+---
+
+Updates how the output is determined in `createRedirectsFromAstroRoutes`. Since `v0.5.0`, the output would use the `buildOutput` property and `config.output` as a fallback. It no longer uses this fallback.
diff --git a/.changeset/tiny-plums-crash.md b/.changeset/tiny-plums-crash.md
new file mode 100644
index 000000000000..815a4a354268
--- /dev/null
+++ b/.changeset/tiny-plums-crash.md
@@ -0,0 +1,40 @@
+---
+'@astrojs/underscore-redirects': minor
+---
+
+Updates the input requirements of `createRedirectsFromAstroRoutes`:
+
+- `routeToDynamicTargetMap` keys are `IntegrationResolvedRoute` instead of `IntegrationRouteData` (obtained from the `astro:routes:resolved` hook)
+- There's a new `assets` property, that can be obtained from the `astro:build:done` hook
+
+```js
+function myIntegration() {
+    let routes
+    let buildOutput
+    let config
+
+    return {
+        name: "my-integration",
+        hooks: {
+            "astro:routes:resolved": (params) => {
+                routes = params.routes
+            },
+            "astro:config:done": (params) => {
+                buildOutput = params.buildOutput
+                config = params.config
+            },
+            "astro:build:done": (params) => {
+                const redirects = createRedirectsFromAstroRoutes({
+                    config,
+                    buildOutput,
+                    routeToDynamicTargetMap: new Map(
+                        routes.map(route => [route, ''])
+                    ),
+                    dir: params.dir,
+                    assets: params.assets
+                })
+            }
+        }
+    }
+}
+```
\ No newline at end of file
diff --git a/packages/underscore-redirects/src/astro.ts b/packages/underscore-redirects/src/astro.ts
index b76e1b52a672..bd3e3b2ea346 100644
--- a/packages/underscore-redirects/src/astro.ts
+++ b/packages/underscore-redirects/src/astro.ts
@@ -1,10 +1,15 @@
 import { posix } from 'node:path';
-import type { AstroConfig, IntegrationRouteData, ValidRedirectStatus } from 'astro';
+import type {
+	AstroConfig,
+	HookParameters,
+	IntegrationResolvedRoute,
+	ValidRedirectStatus,
+} from 'astro';
 import { Redirects } from './redirects.js';
 
 const pathJoin = posix.join;
 
-function getRedirectStatus(route: IntegrationRouteData): ValidRedirectStatus {
+function getRedirectStatus(route: IntegrationResolvedRoute): ValidRedirectStatus {
 	if (typeof route.redirect === 'object') {
 		return route.redirect.status;
 	}
@@ -16,9 +21,10 @@ interface CreateRedirectsFromAstroRoutesParams {
 	/**
 	 * Maps a `RouteData` to a dynamic target
 	 */
-	routeToDynamicTargetMap: Map<IntegrationRouteData, string>;
+	routeToDynamicTargetMap: Map<IntegrationResolvedRoute, string>;
 	dir: URL;
 	buildOutput: 'static' | 'server';
+	assets: HookParameters<'astro:build:done'>['assets'];
 }
 
 /**
@@ -29,6 +35,7 @@ export function createRedirectsFromAstroRoutes({
 	routeToDynamicTargetMap,
 	dir,
 	buildOutput,
+	assets,
 }: CreateRedirectsFromAstroRoutesParams) {
 	const base =
 		config.base && config.base !== '/'
@@ -36,11 +43,10 @@ export function createRedirectsFromAstroRoutes({
 				? config.base.slice(0, -1)
 				: config.base
 			: '';
-	// TODO: the use of `config.output` is deprecated. We need to update the adapters that use this package to pass the new buildOutput
-	const output = buildOutput ?? config.output;
 	const _redirects = new Redirects();
 
 	for (const [route, dynamicTarget = ''] of routeToDynamicTargetMap) {
+		const distURL = assets.get(route.pattern);
 		// A route with a `pathname` is as static route.
 		if (route.pathname) {
 			if (route.redirect) {
@@ -57,13 +63,13 @@ export function createRedirectsFromAstroRoutes({
 			}
 
 			// If this is a static build we don't want to add redirects to the HTML file.
-			if (output === 'static') {
+			if (buildOutput === 'static') {
 				continue;
-			} else if (route.distURL) {
+			} else if (distURL) {
 				_redirects.add({
 					dynamic: false,
 					input: `${base}${route.pathname}`,
-					target: prependForwardSlash(route.distURL.toString().replace(dir.toString(), '')),
+					target: prependForwardSlash(distURL.toString().replace(dir.toString(), '')),
 					status: 200,
 					weight: 2,
 				});
@@ -76,7 +82,7 @@ export function createRedirectsFromAstroRoutes({
 					weight: 2,
 				});
 
-				if (route.route === '/404') {
+				if (route.pattern === '/404') {
 					_redirects.add({
 						dynamic: true,
 						input: '/*',
@@ -92,7 +98,7 @@ export function createRedirectsFromAstroRoutes({
 			const pattern = generateDynamicPattern(route);
 
 			// This route was prerendered and should be forwarded to the HTML file.
-			if (route.distURL) {
+			if (distURL) {
 				const targetRoute = route.redirectRoute ?? route;
 				const targetPattern = generateDynamicPattern(targetRoute);
 				let target = targetPattern;
@@ -128,7 +134,7 @@ export function createRedirectsFromAstroRoutes({
  * /team/articles/*
  * With stars replacing spread and :id syntax replacing [id]
  */
-function generateDynamicPattern(route: IntegrationRouteData) {
+function generateDynamicPattern(route: IntegrationResolvedRoute) {
 	const pattern =
 		'/' +
 		route.segments
diff --git a/packages/underscore-redirects/test/astro.test.js b/packages/underscore-redirects/test/astro.test.js
index 71ee13f339c4..6a4944dc907a 100644
--- a/packages/underscore-redirects/test/astro.test.js
+++ b/packages/underscore-redirects/test/astro.test.js
@@ -3,28 +3,24 @@ import { describe, it } from 'node:test';
 import { createRedirectsFromAstroRoutes } from '../dist/index.js';
 
 describe('Astro', () => {
-	const serverConfig = {
-		output: 'server',
-		build: { format: 'directory' },
-	};
-
 	it('Creates a Redirects object from routes', () => {
 		const routeToDynamicTargetMap = new Map(
 			Array.from([
-				[
-					{ pathname: '/', distURL: new URL('./index.html', import.meta.url), segments: [] },
-					'./.adapter/dist/entry.mjs',
-				],
-				[
-					{ pathname: '/one', distURL: new URL('./one/index.html', import.meta.url), segments: [] },
-					'./.adapter/dist/entry.mjs',
-				],
+				[{ pattern: '/', pathname: '/', segments: [] }, './.adapter/dist/entry.mjs'],
+				[{ pattern: '/one', pathname: '/one', segments: [] }, './.adapter/dist/entry.mjs'],
 			]),
 		);
 		const _redirects = createRedirectsFromAstroRoutes({
-			config: serverConfig,
+			config: {
+				build: { format: 'directory' },
+			},
 			routeToDynamicTargetMap,
 			dir: new URL(import.meta.url),
+			buildOutput: 'server',
+			assets: new Map([
+				['/', new URL('./index.html', import.meta.url)],
+				['/one', new URL('./one/index.html', import.meta.url)],
+			]),
 		});
 
 		assert.equal(_redirects.definitions.length, 2);