diff --git a/activestorage/lib/active_storage/engine.rb b/activestorage/lib/active_storage/engine.rb
index 54a4210fa1..ee2fe59147 100644
--- a/activestorage/lib/active_storage/engine.rb
+++ b/activestorage/lib/active_storage/engine.rb
@@ -42,6 +42,9 @@ module ActiveStorage
       image/vnd.adobe.photoshop
       image/vnd.microsoft.icon
       image/webp
+      image/avif
+      image/heic
+      image/heif
     )
 
     config.active_storage.web_image_content_types = %w(
diff --git a/guides/source/configuring.md b/guides/source/configuring.md
index f0ffbd5c95..040877d25f 100644
--- a/guides/source/configuring.md
+++ b/guides/source/configuring.md
@@ -1050,9 +1050,9 @@ You can find more detailed configuration options in the
     config.active_storage.paths[:ffprobe] = '/usr/local/bin/ffprobe'
     ```
 
-* `config.active_storage.variable_content_types` accepts an array of strings indicating the content types that Active Storage can transform through ImageMagick. The default is `%w(image/png image/gif image/jpg image/jpeg image/pjpeg image/tiff image/bmp image/vnd.adobe.photoshop image/vnd.microsoft.icon image/webp)`.
+* `config.active_storage.variable_content_types` accepts an array of strings indicating the content types that Active Storage can transform through ImageMagick. The default is `%w(image/png image/gif image/jpg image/jpeg image/pjpeg image/tiff image/bmp image/vnd.adobe.photoshop image/vnd.microsoft.icon image/webp image/avif image/heic image/heif)`.
 
-* `config.active_storage.web_image_content_types` accepts an array of strings regarded as web image content types in which variants can be processed without being converted to the fallback PNG format. If you want to use `WebP` variants in your application you can add `image/webp` to this array. The default is `%w(image/png image/jpeg image/jpg image/gif)`.
+* `config.active_storage.web_image_content_types` accepts an array of strings regarded as web image content types in which variants can be processed without being converted to the fallback PNG format. If you want to use `WebP` or `AVIF` variants in your application you can add `image/webp` or `image/avif` to this array. The default is `%w(image/png image/jpeg image/jpg image/gif)`.
 
 * `config.active_storage.content_types_to_serve_as_binary` accepts an array of strings indicating the content types that Active Storage will always serve as an attachment, rather than inline. The default is `%w(text/html
 text/javascript image/svg+xml application/postscript application/x-shockwave-flash text/xml application/xml application/xhtml+xml application/mathml+xml text/cache-manifest)`.