Bradley Johnson rose well to head Tom Ince's free-kick into the far corner for his second goal in as many games.
Johnny Russell almost made it two, hitting the post from a tight angle after pouncing on a poor backpass.
The Latics piled on the pressure after the break, but Max Power spurned their best chance, heading against the bar when unmarked.
The game matched the Championship's joint-lowest scorers, and Derby's winner came with their only shot on target.
The Latics forced a string of corners amid mounting pressure, but could not break through against the Championship's second-meanest defence.
Power and Dutch striker Yanic Wildschut forced good saves from Rams keeper Scott Carson who kept his seventh clean sheet in 10 matches.
Derby have picked up 19 points from a possible 24 since Steve McClaren's return as manager and moved within a point of the play-off places in eighth, while Wigan, without a win in four home games, slipped to second-bottom.
Wigan manager Warren Joyce:
"We're obviously disappointed to lose the game. I thought in the first half we had a lot of possession without a lot of purpose in our play.
"We lost possession ourselves on the halfway line which leads to the free-kick, and a really soft, basic error means we're 1-0 down.
"The players did exactly what we talked about at half-time to stay in the game and I thought for half-an-hour during that period we deserved a goal."
Derby boss Steve McClaren:
"We had a great start and for some reason we kind of took our foot off the pedal when we needed to go up.
"We knew this would be a difficult place to come, and when we didn't manage to get the second goal the last 10 to 15 minutes were always going to be a bit nervy.
"You're not going to play well every week and it's getting to a time - December, January, February - where you have to grind out results."
Match ends, Wigan Athletic 0, Derby County 1.
Second Half ends, Wigan Athletic 0, Derby County 1.
Substitution, Derby County. Jamie Hanson replaces Will Hughes.
Substitution, Wigan Athletic. Kaiyne Woolery replaces Max Power.
Corner,  Wigan Athletic. Conceded by Will Hughes.
Attempt blocked. Max Power (Wigan Athletic) right footed shot from outside the box is blocked. Assisted by Yanic Wildschut.
Attempt blocked. Luke Garbutt (Wigan Athletic) left footed shot from outside the box is blocked. Assisted by Shaun MacDonald.
Attempt blocked. Jake Buxton (Wigan Athletic) right footed shot from the left side of the box is blocked.
Will Hughes (Derby County) is shown the yellow card for a bad foul.
Corner,  Wigan Athletic. Conceded by Richard Keogh.
Attempt blocked. Yanic Wildschut (Wigan Athletic) right footed shot from outside the box is blocked.
Foul by Yanic Wildschut (Wigan Athletic).
Tom Ince (Derby County) wins a free kick in the defensive half.
Substitution, Wigan Athletic. Adam Le Fondre replaces David Perkins.
Offside, Derby County. Craig Bryson tries a through ball, but Andreas Weimann is caught offside.
Delay over. They are ready to continue.
Delay in match Stephen Warnock (Wigan Athletic) because of an injury.
Foul by Luke Garbutt (Wigan Athletic).
Andreas Weimann (Derby County) wins a free kick in the defensive half.
Attempt blocked. Will Hughes (Derby County) left footed shot from the centre of the box is blocked.
Corner,  Derby County. Conceded by Shaun MacDonald.
Substitution, Derby County. Craig Bryson replaces Jacob Butterfield.
Substitution, Derby County. Andreas Weimann replaces Johnny Russell.
Attempt missed. Michael Jacobs (Wigan Athletic) right footed shot from outside the box is high and wide to the right. Assisted by David Perkins.
Max Power (Wigan Athletic) hits the bar with a header from the centre of the box. Assisted by Stephen Warnock with a cross.
Corner,  Wigan Athletic. Conceded by Scott Carson.
Attempt missed. Yanic Wildschut (Wigan Athletic) left footed shot from the left side of the box is close, but misses to the left. Assisted by William Grigg with a headed pass.
Corner,  Derby County. Conceded by Jake Buxton.
Foul by Yanic Wildschut (Wigan Athletic).
Richard Keogh (Derby County) wins a free kick in the defensive half.
Corner,  Wigan Athletic. Conceded by Chris Baird.
Attempt missed. Stephen Warnock (Wigan Athletic) left footed shot from outside the box misses to the right. Assisted by Yanic Wildschut.
Corner,  Wigan Athletic. Conceded by Johnny Russell.
Substitution, Wigan Athletic. William Grigg replaces Jordi Gómez.
Corner,  Wigan Athletic. Conceded by Bradley Johnson.
Stephen Warnock (Wigan Athletic) wins a free kick in the defensive half.
Foul by Will Hughes (Derby County).
Attempt blocked. Michael Jacobs (Wigan Athletic) right footed shot from the centre of the box is blocked.
Attempt blocked. Craig Morgan (Wigan Athletic) right footed shot from the centre of the box is blocked.
Corner,  Wigan Athletic. Conceded by Chris Baird.
Derby County made it five straight wins as they withstood a second-half onslaught from Wigan Athletic.