Jamal Lowe's first Wigan goal ended Nottingham Forest's 10-game unbeaten run to dash the visitors' hopes of going top of the Championship.
A three-goal victory would have taken Forest to the summit but Lowe, a summer signing from Portsmouth, exchanged passes with Gavin Massey to net the decisive effort from close range 10 minutes before the break.
Wigan, who climb two places to 18th after a third successive home win, twice struck the woodwork through Charlie Mulgrew's free-kick and Kal Naismith's late effort.
Forest created enough chances to have earned at least a point but Rafa Mir and Lewis Grabban both missed gilt-edged opportunities as Sabri Lamouchi's side remain fourth.
Mir, on loan from Wolves, headed Joe Lolley's cross over from six yards shortly before Lowe's opener and the Spanish striker fired wastefully wide from John Bostock's through ball after the interval.
His replacement Grabban, Forest's top scorer on five league goals, fared little better, heading straight at Latics keeper David Marshall when a ball looped up invitingly for him six yards out.
Forest had two penalty shouts ignored for Antonee Robinson's tug on Sammy Ameobi and Joe Williams' foul on Yuri Ribeiro, although contact in both instances initiated outside the box.
Wigan have never lost to Forest in eight meetings at the DW Stadium and have only been beaten once in their past 16 home games, by Leeds United in August.
They could have won more comfortably had the base of the post not denied Mulgrew's free-kick towards the end of the first half and Naismith's side-footed strike in the closing stages.
Wigan remain the division's second lowest scorers despite Lowe's well-worked goal but frequently looked dangerous with Naismith forcing two fine late saves from Forest keeper Brice Samba.
This was the Latics' 15th home clean sheet since the start of last season - no Championship side has kept more - as they became the first side to prevent Forest scoring in the league this term.
Wigan boss Paul Cook:
"I thought we were good in the game, I enjoyed watching us play.
"It's another very strong home performance, and you'd struggle to name our best player because we had so many good performers. We looked a threat against a very strong Forest side. And at the other end, we defended very, very well.
"When you have those two things coming together in a football match, it usually ends up with a good result."
Nottingham Forest boss Sabri Lamouchi:
"If you analyse the game, especially the first half hour, we started in the right way, but we made one mistake. We gave them the opportunity to score and they scored.
"After that, we created a lot of opportunities, but we missed them all. If you don't score a goal then you have no chance of winning a game.
"Maybe a draw would have been more logical a result, but congratulations to Wigan."