Pearce has been a key part of the Leeds squad this season and was vice captain at the Elland Road club.
Malky Mackay is said to be delighted with the capture of Pearce who is expected to quickly establish himself in the Wigan first team.
Speaking about Pearce joining the club, Mackay told the club's official website: “I’m delighted that he has agreed to join us.
"He’s someone we’ve been tracking for a while, a really powerful centre half, a leader and a warrior on the pitch, who has captained every club he has played at, and is exactly the type of player I want at the club.
“He’s hungry to play and will hopefully quickly become a fan’s favourite for the example he sets on the pitch.
"We’ve spoken to a lot of people about him and every single reference has come back positively, in that he is the right character we are seeking, someone who takes responsibility on the pitch and energises those around him.”
“He’s built up considerable experience now and knows this league inside out and we’re delighted we’ve managed to get him.
"When we found out he might be available we immediately did all we could to get him because he’s a player who can play a major role in taking the club forwards.”