Watson told the Wigan website: "Every player wants to play at the top level and when you look at the way Wigan have been playing this season, and where they are in the league, I jumped at the chance to join.
"Steve Bruce has been there and done it as a player, and when someone like that comes knocking, it doesn't take long for you to make your mind up.
"I really am excited about joining up with the rest of the squad. Competition for places will be really tough but I want to do everything I can to get in the team and keep my place.
"When I look at the players we've got in the squad, I don't see why we can't be aiming high. We need to make sure we're safe with another three or four wins or so, and then look to push on from there.
"Wigan has been a good football story in the last few years, and it's great to be a part of that now."
Watson said he was sad to be leaving Crystal Palace, but feels 'it's time to move on.'
"I owe Palace everything," he said, "I've been there over half my life. I want to thank everyone at the club. The staff, the manager, the Chairman and especially the supporters, but I feel I need to move, experience something new.
"I've given everything to the club while I was there but it's time for me to try something else. It's going to be strange leaving London, but I'm looking forward to it. A complete change for me, in football but also in my life."