Ryan Yates received an early red card for a deliberate handball on the goal line with Reading top scorer Lucas Joao converting the resulting penalty and The Royals put the seal on all three points in the second half when defender Michael Morrison headed home from a corner.
Chris Hughton made one change to the side that drew with Watford in midweek as Scott McKenna returned to the starting line-up in place of Tobias Figueiredo while Samba Sow returned from injury to take on the bench with Loic Mbe Soh and Alex Mighten dropping out of the matchday squad.
Reds goalkeeper Brice Samba had to be alert in the game's opening stages to prevent the home side from taking the lead. Liam Moore's free-kick went straight into the Forest wall but the ball broke kindly for Yakou Meite and Samba had to readjust to produce a strong save and push away the Ivorian's swerving strike.
At the other end, Forest were unfortunate not to hit the front themselves through Lyle Taylor. Anthony Knockaert's inswinging delivery was perfect for the striker's run to the back post but despite looking destined to score, Reading goalkeeper Rafael was able to get across his line and turn the ball behind for a corner.
The turning point of the game came after only 14 minutes when Yates received his marching orders from referee Gavin Ward. Samba spilt an overhit free-kick under pressure from Tom Holmes and as the ball headed towards the net, Yates knocked the ball out with his hand and there was no hesitation from the officials to issue a penalty and a red card for the Forest midfielder. Joao subsequently sent Samba the wrong way from the spot.
Reading's strong tempo and quickness of thought was causing Forest problems and they had an excellent chance to make it 2-0 on 22 minutes. Michael Olise's diagonal ball set Meite away inside the penalty area and having turned away from his man, he could only dispatch the ball wide of the target and into the empty seats behind the goal.
Forest were trying to stem the tide and prevent Reading from taking that important two-goal lead before the interval. Joao's delivery into the six-yard box took a wicked deflection and almost caught Samba out at his near post but the Forest number one was able to get across and stop the ball spinning across his goal line.
The second goal for the home side had been coming and it arrived on 53 minutes. Olise's outswinging corner from the left was delivered into the Forest penalty area and Samba was rooted to the spot as Morrison planted a bullet header into the back of his net.
Hughton introduced Sow, Sammy Ameobi and Will Swan to the contest in an attempt to reverse the momentum but Reading still came forward at will. They had the ball in the back of the net once again on 79 minutes as Olise's free-kick was turned in but referee Ward had already blown his whistle for a Forest free-kick.
Having played 76 minutes with ten men, Forest failed to mount any sort of serious comeback and Reading were able to comfortably see out the game's closing stages to leave The Reds looking at five games without a win or a goal.
Forest: Samba; Christie, Worrall (c), McKenna (Figueiredo 46'), Ribeiro; Yates, Cafu, Arter (Sow 60'); Lolley, Taylor (Swan 71'), Knockaert (Ameobi 60')
Subs not used: Smith, Jenkinson, Guerrero, Dawson, Ioannou
Booking: Cafu 90'
Sent off: Yates 14'
Reading: Rafael; Holmes, Richards (Gibson 85'), Moore (c), Morrison; Rinomhota, Laurent, Ejaria (Esteves 81'), Olise (Aluko 81'); Meite (Semedo 74'), Joao (Baldock 86')
Subs not used: Southwood, McIntyre, Tetek, Onen
Goal: Joao (pen) 16', Morrison 53'
Booking: Richards 83'
Referee: Gavin Ward
Attendance: 2,000