Wigan quickly settled into their stride and Joe Williams released Lowe down the right, but the shot was weak and straight at goalkeeper Samba.
Right-back Nathan Byrne – making his 100th league start for the club – then got forward enough to have a decent effort blocked, before Chey Dunkley headed over from the resulting corner from Michael Jacobs.
It certainly was not going according to plan for high-flying Forest, whose manager Sabri Lamouchi was given a yellow card by referee Matt Donohue for speaking out of turn to the fourth official.
Things improved for the visitors when a raking ball from Ben Watson – who scored Wigan's FA Cup-winning goal against Manchester City in 2013 – set up a Forest move that saw Matty Cash cross into Yuri Ribeiro.
However, Ribeiro's finish was woeful, with Rafael Mir heading just over from the cross back in.
Wigan regained the ascendancy, and took the lead with 10 minutes of the first half remaining.
Lowe started and finished the move, winning possession from Ben Watson in midfield and advancing on goal.
Instead of shooting, he played the ball out to Gavin Massey, whose return ball was slotted home from six yards by the forward.
It was almost 2-0 five minutes later, with Mulgrew sending in a curling free-kick from 20 yards that beat the wall, the Forest goalkeeper but – unfortunately for him – not the far post.
Wigan came close again two minutes after the restart, when Massey's flick towards the far post was parried out by Samba at full stretch.
Byrne was booked for Wigan – his fifth of the season which triggers a one-match suspension – and Forest continued to up the ante.
A lovely move involving John Bostock and Mir saw the former fire well wide from a great chance.
And that was the last action for both, with Forest making an immediate double substitution.
One of the changes, Lewis Grabban, squandered a gilt-edged opportunity to equalise when Mulgrew could only flick on a cross into his path.
But the lethal striker nodded tamely at David Marshall, perhaps surprised at how the ball had so easily come to him.
Wigan made a double change themselves and one of them, Kal Naismith, could have had a hat-trick inside the final quarter.
But on all three occasions, goalkeeper Samba was on hand to keep out the danger as fourth-placed Forest's 10-match unbeaten league run was ended.