How can I import bookmarks from Firefox to Safari?

First you need to export them, but bookmarks on Firefox's iPhone app cannot be exported directly.

The solution is sync the Firefox browser app on your Mac first: How do I set up Sync on my computer?

Once you do that, you can export them: Export Firefox bookmarks to an HTML file to back up or transfer bookmarks

• I suggest you export them to iCloud Drive since that's the easiest way to get that file on your iPhone.

Then you can import them: Import data from another browser into Safari on iPhone - Apple Support