- Open the Bookmark Manager and export your bookmarks;
- Open the exported html file in your favorite editor and look for the bookmarklet you want a favicon applied to;
- Convert the 16x16 px (or greater) favicon you want to use into the BASE64 format (I used Base64 Image Encoder);
- Now you can add the favicon via adding the
ICON="data:image/insert-your-base64-image-code-here"
attribute in the link; - Save the file and import it in the bookmark manager.
Done! If the favicon doesn’t show up, try clicking on the bookmarklet. Afterwards the changes should stick and you can delete the imported bookmarks folder. If you have sync activated the favicons on your bookmarklets will also show up on your other PC, Mac, smartphone etc.