diff --git a/.changeset/avif-media-uploads.md b/.changeset/avif-media-uploads.md
new file mode 100644
index 0000000000..3564cb8fbd
--- /dev/null
+++ b/.changeset/avif-media-uploads.md
@@ -0,0 +1,10 @@
+---
+"emdash": patch
+"@emdash-cms/admin": patch
+---
+
+Fixes AVIF images being rejected with "File type not allowed" on upload. `image/avif` is back in the default media allowlist alongside PNG, JPEG, GIF, and WebP, so editors can upload `.avif` files again from the media library and from image fields that use the default allowlist.
+
+The admin file picker now offers `.avif` files and renders their thumbnails, the built-in "Images" preset in a field's allowed-types editor includes AVIF, and `.avif` works as extension shorthand in a field's `allowedMimeTypes`.
+
+SVG stays excluded from the default allowlist.
diff --git a/docs/src/content/docs/guides/media-library.mdx b/docs/src/content/docs/guides/media-library.mdx
index 77f2189c10..ab7e5f5537 100644
--- a/docs/src/content/docs/guides/media-library.mdx
+++ b/docs/src/content/docs/guides/media-library.mdx
@@ -40,7 +40,7 @@ EmDash accepts these file types by default:
 
 | Category  | Extensions                                      |
 | --------- | ----------------------------------------------- |
-| Images    | `.jpg`, `.jpeg`, `.png`, `.gif`, `.webp`        |
+| Images    | `.jpg`, `.jpeg`, `.png`, `.gif`, `.webp`, `.avif` |
 | Documents | `.pdf`                                         |
 | Video     | `.mp4`, `.webm`, `.mov`                         |
 | Audio     | `.mp3`, `.wav`, `.ogg`                          |
diff --git a/packages/admin/src/components/AllowedTypesEditor.tsx b/packages/admin/src/components/AllowedTypesEditor.tsx
index 577c8b5279..9822265e01 100644
--- a/packages/admin/src/components/AllowedTypesEditor.tsx
+++ b/packages/admin/src/components/AllowedTypesEditor.tsx
@@ -12,7 +12,10 @@ interface Preset {
 }
 
 const PRESETS: ReadonlyArray<Preset> = [
-	{ key: "images", mimeTypes: ["image/png", "image/jpeg", "image/gif", "image/webp"] },
+	{
+		key: "images",
+		mimeTypes: ["image/png", "image/jpeg", "image/gif", "image/webp", "image/avif"],
+	},
 	{ key: "pdf", mimeTypes: ["application/pdf"] },
 	{
 		key: "documents",
diff --git a/packages/admin/src/components/MediaUploadDialog.tsx b/packages/admin/src/components/MediaUploadDialog.tsx
index f9aa445d5d..a5e5242afc 100644
--- a/packages/admin/src/components/MediaUploadDialog.tsx
+++ b/packages/admin/src/components/MediaUploadDialog.tsx
@@ -19,13 +19,19 @@ import * as React from "react";
 import { formatFileSize } from "../lib/media-utils.js";
 
 export const LOCAL_MEDIA_UPLOAD_ACCEPT =
-	"image/png,image/jpeg,image/gif,image/webp,video/*,audio/*,application/pdf";
+	"image/png,image/jpeg,image/gif,image/webp,image/avif,video/*,audio/*,application/pdf";
 
 const DEFAULT_CONCURRENCY = 3;
 const MAX_CONCURRENCY = 6;
 const MAX_VISIBLE_ROWS = 100;
 const MAX_PREVIEW_BYTES = 8 * 1024 * 1024;
-const PREVIEW_MIME_TYPES = new Set(["image/jpeg", "image/png", "image/gif", "image/webp"]);
+const PREVIEW_MIME_TYPES = new Set([
+	"image/jpeg",
+	"image/png",
+	"image/gif",
+	"image/webp",
+	"image/avif",
+]);
 
 type UploadStatus = "queued" | "uploading" | "complete" | "failed";
 
diff --git a/packages/admin/src/lib/mime-utils.ts b/packages/admin/src/lib/mime-utils.ts
index 96fdae0ca1..d3e714dc38 100644
--- a/packages/admin/src/lib/mime-utils.ts
+++ b/packages/admin/src/lib/mime-utils.ts
@@ -5,6 +5,7 @@ export const EXTENSION_TO_MIME: Readonly<Record<string, string>> = {
 	".jpeg": "image/jpeg",
 	".gif": "image/gif",
 	".webp": "image/webp",
+	".avif": "image/avif",
 	".svg": "image/svg+xml",
 	".mp3": "audio/mpeg",
 	".wav": "audio/wav",
diff --git a/packages/core/src/api/handlers/media-allowlist.ts b/packages/core/src/api/handlers/media-allowlist.ts
index 9c7c06f3f0..0c049ac362 100644
--- a/packages/core/src/api/handlers/media-allowlist.ts
+++ b/packages/core/src/api/handlers/media-allowlist.ts
@@ -21,6 +21,7 @@ export const GLOBAL_UPLOAD_ALLOWLIST: readonly string[] = [
 	"image/jpeg",
 	"image/gif",
 	"image/webp",
+	"image/avif",
 	"video/",
 	"audio/",
 	"application/pdf",
diff --git a/packages/core/src/media/mime.ts b/packages/core/src/media/mime.ts
index 495e9f62c5..aedb8a8678 100644
--- a/packages/core/src/media/mime.ts
+++ b/packages/core/src/media/mime.ts
@@ -23,6 +23,7 @@ export const EXTENSION_TO_MIME: Readonly<Record<string, string>> = {
 	".jpeg": "image/jpeg",
 	".gif": "image/gif",
 	".webp": "image/webp",
+	".avif": "image/avif",
 	".svg": "image/svg+xml",
 	".mp3": "audio/mpeg",
 	".wav": "audio/wav",
diff --git a/packages/core/tests/unit/media/media-allowlist.test.ts b/packages/core/tests/unit/media/media-allowlist.test.ts
index 7f7a9243c3..65957ca6c6 100644
--- a/packages/core/tests/unit/media/media-allowlist.test.ts
+++ b/packages/core/tests/unit/media/media-allowlist.test.ts
@@ -15,6 +15,10 @@ describe("GLOBAL_UPLOAD_ALLOWLIST", () => {
 		expect(matchesMimeAllowlist("image/webp", GLOBAL_UPLOAD_ALLOWLIST)).toBe(true);
 	});
 
+	it("allows image/avif, which the media routes already serve inline", () => {
+		expect(matchesMimeAllowlist("image/avif", GLOBAL_UPLOAD_ALLOWLIST)).toBe(true);
+	});
+
 	it("still allows video, audio, and pdf", () => {
 		expect(matchesMimeAllowlist("video/mp4", GLOBAL_UPLOAD_ALLOWLIST)).toBe(true);
 		expect(matchesMimeAllowlist("audio/mpeg", GLOBAL_UPLOAD_ALLOWLIST)).toBe(true);
diff --git a/packages/core/tests/unit/media/mime.test.ts b/packages/core/tests/unit/media/mime.test.ts
index 4fd247a92f..71c6d3afc1 100644
--- a/packages/core/tests/unit/media/mime.test.ts
+++ b/packages/core/tests/unit/media/mime.test.ts
@@ -76,6 +76,7 @@ describe("expandExtensionShorthand", () => {
 	it("expands known dot-extensions", () => {
 		expect(expandExtensionShorthand(".pdf")).toBe("application/pdf");
 		expect(expandExtensionShorthand(".PDF")).toBe("application/pdf");
+		expect(expandExtensionShorthand(".avif")).toBe("image/avif");
 		expect(expandExtensionShorthand(".docx")).toBe(
 			"application/vnd.openxmlformats-officedocument.wordprocessingml.document",
 		);