Powell has joined Wigan on a season-long loan from United.
Wigan boss Owen Coyle said: "We’re delighted to welcome Nick to Wigan Athletic, and thank Manchester United for allowing a player whom they have invested a large sum of money in and has incredible talent, to join us for the season.
"We’re all excited to be offering him the opportunity to play football at a high level and for him to continue his development here at the club."
Whelan told the BBC: "We obviously had Tom Cleverley on loan and I think United were happy with the job we did with him, so it's good news that we've got the lad.
"We've done the deal for a season long loan."