A second-minute goal from Matt Derbyshire was enough to end a frustrating run for Gary Brazil's side and lifted them to within three points of sixth-placed Brighton.
Missed chances almost cost the home side dear, as Lee Clark's Birmingham came close to what would have been an undeserved equaliser through both Chris Burke and Paul Robinson at the City Ground on Saturday.
But while the Blues were ultimately left still looking over their shoulders following this 1-0 defeat, results elsewhere went in Forest's favour, giving them fresh hope of making the top six, after ending their run of 12 games without a league victory.
The statistics showed that Forest had enjoyed 65 per cent of the possession in the first half, but the Reds' main concern will that the key stat was that they held only a 1-0 lead following 45 minutes in which they had almost entirely dominated.
It took barely one minute for Forest to take the lead, with Jamie Paterson sliding a simple, but incisive pass into the path of Derbyshire, who duly kept his head to slot under the advancing Darren Randolph.
The rest of the half followed a similar path, with the Reds repeatedly carving out chances but failing to show the same level of cutting edge.
Ben Osborn sent a header over the bar, following good work from Derbyshire. Danny Fox forced a capable save with a bending free kick and Derbyshire flashed another, clever effort just wide of the far post.
Forest were utterly dominant, with Blues mustering little threat at all, aside from lumping hopeful high balls in the direction of towering striker Nikola Zigic. But the Reds will have been left frustrated after seeing further chances go begging at the other end.
Osborn was unlucky to see a low, placed shot bend just the wrong side of the near post from 20 yards and, from a similar position, David Vaughan angled a shot just a few inches wide of the far upright, as Forest continued to pin the visitors back.
But half-time arrived without another goal - and Birmingham, unsurprisingly, were more urgent after the break.
When Darlow collided with his own defender, Jamaal Lascelles, when coming to claim a Burke cross, it looked as though Birmingham would profit, but Danny Collins was on hand to clear.
Normal service was resumed as Osborn sent Paterson racing clear, only for Randolph to deny Forest a second goal with a powerful save.
Birmingham should have levelled when Burke crossed for Zigic, but the big striker sent his header straight at a grateful Darlow, from close range.
Burke thought he had scored when he flashed a shot across goal, only for a deflection to take it wide of the post. From the resulting corner, Paul Robinson was denied by an outstanding save from Darlow, who pawed his header around the post.
Sub Darius Henderson almost put the game beyond Birmingham with a curling shot that went wide, but Forest were still able to hold on for a precious win - their first since February 11 when they won 3-0 at Huddersfield.