The forward, who turns 20 at the end of July, has agreed to join Gary Caldwell's side for the 2026/27 Sky Bet League One season.
Mustapha has been on Crystal Palace's books since the age of nine and has climbed through the youth ranks at the Eagles.
Over the past three seasons he has been a regular for Palace's senior academy sides, scoring 16 goals and adding 17 assists from midfield in 57 appearances across the U18 Premier League and Premier League 2. He then stepped seamlessly into the U21s set-up, where he was named Palace's Player of the Season for 2024/25. Mustapha was also nominated for the Premier League 2 Player of the Season award after contributing 11 goals and seven assists in all competitions, a return achieved while just 18.
The teenager spent last season out on loan, first with German side 1. FC Nürnberg and then with Sky Bet Championship club West Bromwich Albion.
He has also broken into senior international football, winning three caps for Sierra Leone since debuting against Chad in September 2024. Mustapha scored in a 3-2 defeat away to Zambia and assisted in a 4-1 loss to Ivory Coast during AFCON qualifying. He will now link up with new teammates at Christopher Park, eager to get started at the Brick Community Stadium.
"I am more than happy - I am really excited to get going and show what I can do in a Wigan Athletic shirt," Mustapha said. "It's a big Football Club, and I believe I can come here and really kick on.
"The Gaffer seems very genuine, and his vision really excites me. I am really looking forward to working with him.
"On the ball, I like to make things happen. I want to excite fans and get bums off seats."
Latics manager Gary Caldwell has followed Mustapha's progress closely and believes the loan spell can bring out the best in him.
"Hindo is a player that I have tracked for a number of years, and I think he's in a really good moment now to show what he can do," Caldwell said. "He's had a couple of difficult loans, which I believe can bring the best out of players. I think he needs a home where he feels support from myself, the staff, his teammates and the supporters.
"On his day, he's a player who has massive quality in the final third, and I'm sure he will be a massive fan favourite if they get behind him and show him the support he needs to be successful."
Wigan will be hoping the fresh start at the Brick Community Stadium unlocks the potential that has long caught Caldwell's eye.