The Hoops paid £110,000 for the winger – with add-ons up to another £200,000 depending on appearances.
He told celtictv: “It feels amazing. It’s like a dream come true. I came over here on trial just before Christmas and spent eight days here and saw two matches that I’d never been to before. It was brilliant.
“I’m now going to work hard and try my best to make an appearance for the first-team and make the fans happy. This is the club I’ve always supported and this is huge for me.”