Billy Davies saw his side romp into a 3-0 lead over his former side during a one-sided first half.
But there was a nervous finish as Nigel Clough almost engineered a remarkable result on the ground where his father earned legendary status, as the Rams clawed their way back to 3-2.
It was the Reds' first win over Derby in nine attempts - and a result that they will hope can kick-start their season, although a serious looking injury to skipper Paul McKenna in stoppage time cast a cloud over the result.
It took only 53 seconds for Forest to fire themselves into the lead as the Derby defence half-cleared a Chris Gunter cross to the edge of the box, from where Radoslaw Majewski smashed a spectacular shot in off the underside of the bar.
Chris Cohen came close to adding a second as he fizzed a shot narrowly wide of the post from a similar position.
Derby should have equalised when Stephen Pearson fed Gary Teale in the box, only for the midfielder to miss the target with the goal at his mercy.
Former Forest player Kris Commons then made the first of two critical errors as he fouled Joe Garner on the flank in the 28th minute.
Cohen's in-swinging delivery from the right caused chaos in the Rams defence, with Rob Hulse heading into his own net under heavy pressure from Dexter Blackstock on the edge of the six-yard box.
Hulse was denied a quick response for the visitors as Lee Camp made a brave save at his feet after the striker had raced clean through.
But then Commons' second mistake laid a third goal on a plate for the home side just before half-time.
Commons lingered in possession and allowed Paul McKenna to snatch the ball and feed Blackstock. The striker then rolled a perfectly weighted pass into the path of Nathan Tyson, who took the ball around keeper Stephen Bywater before slotting a low shot home.
Commons was substituted at half-time, with Lee Croft coming on - and the Rams almost immediately fought back, albeit through a large amount of good luck.
Miles Addison was well off-target with an attempted overhead kick but the ball bounced cruelly off defender Wes Morgan and into the bottom corner of the net in the 51st minute.
Derby's unlikely fightback continued with another stroke of good fortune, as a headed clearance from Morgan fell kindly to Jake Livermore and he connected well with a crisp shot, but again a deflection deceived Camp as it flew beyond the keeper into the net.
But Forest managed to survive despite being reduced to ten men in stoppage time when captain McKenna limped off the pitch.