diff --git a/.changeset/lemon-elephants-sell.md b/.changeset/lemon-elephants-sell.md
new file mode 100644
index 000000000000..5f68dd2b5067
--- /dev/null
+++ b/.changeset/lemon-elephants-sell.md
@@ -0,0 +1,5 @@
+---
+'@astrojs/netlify': patch
+---
+
+Make Netlify adapter actually append redirects
diff --git a/packages/integrations/netlify/src/index.ts b/packages/integrations/netlify/src/index.ts
index 60aad4b79b13..c473de67ae63 100644
--- a/packages/integrations/netlify/src/index.ts
+++ b/packages/integrations/netlify/src/index.ts
@@ -53,11 +53,10 @@ ${pattern}    /.netlify/functions/${entryFile}    200`;
 					}
 				}
 
-				if (fs.existsSync(_redirects)) {
-					await fs.promises.appendFile(_redirectsURL, _redirects, 'utf-8');
-				} else {
-					await fs.promises.writeFile(_redirectsURL, _redirects, 'utf-8');
-				}
+				// Always use appendFile() because the redirects file could already exist,
+				// e.g. due to a `/public/_redirects` file that got copied to the output dir.
+				// If the file does not exist yet, appendFile() automatically creates it.
+				await fs.promises.appendFile(_redirectsURL, _redirects, 'utf-8');
 			},
 		},
 	};