The visitors impressed in the first half but fell apart after the break, with the Black Cats building on a Jordi Gomez red card to grab the win and all three points
Martin O'Neill gave England international Adam Johnson his first start following his summer move from Manchester City while Sebastian Larsson moved into the centre alongside Jack Colback, who replaced the suspended Lee Cattermole.
Wigan fielded a strong line-up with Jordi Gomez starting up front with Shaun Maloney and Arouna Kone and Franco Di Santo left on the bench.
The Latics started the game in impressive fashion, troubling Mignolet in the Sunderland goal after just three minutes. The home defence fumbled a poor clearance before gifting the ball to James McCarthy, who drove a fearsome left-footed strike towards goal only to see it saved by Mignolet.
Wigan then had an even better chance some 10 minutes later. Jean Beausejour dispatched a well-struck cross from the wing into Kone, who connected beautifully on the volley only to see Mignolet produce an outstanding dive to keep his side level.
The home side showed signs of a fight back midway through the first period, Johnson was deemed to have been unfairly taken down just outside the Wigan penalty area to gift Sunderland a free-kick only to see Sebastian Larsson crash it into the wall.
Sunderland then found themselves with another free-kick on the edge of the box just seconds later, Larsson stepped up to whip in a curling drive straight at goal only to see Ivan Ramis narrowly scramble it off the line before Fletcher cleared the danger with a header after the ball had been played back in.
However, in the minutes leading up to the break Sunderland found themselves on the back foot. McCarthy looked set to break the deadlock when he cut inside from 20 yards out before driving a powerful shot at goal, provoking a marvellous save from Mignolet on his right.
Referee Webb pounced into actions with the second half just seconds old, showing Wigan’s Gomez a red card for a reckless studs-up challenge on Danny Rose just inside the Latics half.
Sunderland drew much confidence from Gomez’s dismissal, with the Black Cats pushing forward with pace before seeing McClean fire a poorly struck shot towards goal only to see it drift to Fletcher, who blasted a great shot from across the area, breezing past Wigan’s Al-Habsi with frightening ease to put his side ahead.
A Wigan comeback looked likely when Beausejour laid off a cracking pass into the run of Di Santo, who failed to connect with any real vigour and only managed to see the ball glide into the stands much to the enjoyment of the Sunderland faithful.
Miyaichi attempted to push forward an attack for the Latics, but his footing was a little off as he gifted Sunderland an opportunity on the break. Larsson brought the home side’s attack up near the box before dispatching to Fletcher, who was deemed offside.
The game enjoyed five minutes of stoppage time at the end of the clash, but the home side’s domination was not compromised as O’Neill’s Black Cats hung on to grab a well-deserved three points over a Wigan side who failed to get going in the second half.