That feat was accomplished due to solid work from Richard Hinds and Ian Baraclough, who displayed tenacity in midfield, with Cliff Byrne also getting through a lot of work.
Forest never looked happy under pressure although they could point to excellent displays by Wes Morgan and Gary Holt.
Scunthorpe held firm when they were tested in the initial stages, but it needed a fine interception by Hinds to stop a powerful burst from Nathan Tyson.
The big Forest defence stood up well to the threat from their hosts, but they were almost caught out when Cleveland Taylor found space and drove over the top from 25-yards.
Peter Beagrie was then unlucky to see a shot into a crowded box cleared off the line.
Having produced most of the pressure the odds were beginning to favour Scunthorpe, but it took defender Lee Ridley to break the deadlock in the 29th minute when Forest keeper Paul Gerrard allowed the ball to spin out of his hands into the net.
At this point Forest began to look jittery, although neither defence looked very sure.
There was a steady pace at the start of the second half, enlivened after 57 minutes when Nicky Southall's great strike was only inches off target.
Forest got back into the game with a 65th-minute penalty after Hinds sent Gareth Taylor sprawling in the box. The Welshman got up to despatch a low spot-kick beyond Tom Evans.
Scunthorpe regained the lead seven minutes later when substitute Tommy Johnson's first touch saw him lay off a superb ball for Cleveland Taylor to clip home a brilliant left foot shot.
The Iron clinched the points in the 83rd minute when Byrne latched on to Beagrie's flick and made no mistake with his finish.