How to save an image to the photo gallery using Flutter?

Unfortunately flutter doesn't currently exposes that functionality. It does seem like a candidate for a plugin though.

If you're motivated enough, you could use platform channels to communicate from flutter to native Android (and iOS) code, from which you can get full access the gallery. Bonus points if you make it into a plugin and publish it!

There is a plugin that supports this.

https://pub.dev/packages/image_gallery_saver

I have tested it and it's working fine.

https://pub.dev/packages/gallery_saver

this plugin saves images and video to gallery/photos.

You just need to provide it with path to temp file that you got from Camera(or even network url, it also works):

GallerySaver.saveVideo(recordedVideo.path);
GallerySaver.saveImage(recordedImage.path);