Greg Taylor has completed his move to Celtic from Kilmarnock on a four-year deal.
The left-back, 21, had been the subject of talks between the clubs in recent days with a deal now struck.
Sunderland and Nuremberg had previously made bids for the Scotland international, but the English League One side then ended their interest.
“It’s been a whirlwind of a day but I’m over the moon to be here,” Taylor told Celtic TV.
“As soon as I knew of Celtic’s interest, I was desperate to come, so it’s been a great day, certainly now that it’s done.
“It’s massive club, everyone knows that, and I’m here to win trophies, it’s as simple as that and I can’t wait to hopefully be a part of it. I’m delighted to be a Celtic player, and I want to try and impress the fans, and obviously the manager.”
Taylor will compete with Boli Bolingoli for the left-back berth vacated by Kieran Tierney after his move to Arsenal.
A Kilmarnock statement said: “The club would like to thank Greg for his services to Kilmarnock Football Club, and wishes him the best for the future.”
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