Aberdeen manager Derek McInnes is delighted to have James Wilson back at Pittodrie.
The striker spent last season on loan in the north of Scotland.
He has now returned on a permanent deal after being released by Manchester United.
He told Aberdeen's official website: "I'm delighted to have James back.
"He is a young player who has had to deal with a lot in a short space of time, but he's got his whole career ahead of him.
"We feel that he showed glimpses towards the end of last season how effective a player he can be and what a positive impact he can have on the team.
"We want to try and build on that now that he is an Aberdeen player and not a Manchester United player."