Garath McCleary's stunner settled the City Ground nerves with fifteen minutes remaining before Robbie Findley wrapped up a vital three points near the end.
Both sides had chances to take control of the game prior to the opening goal but Steve Cotterill will be delighted with both the victory and the clean sheet.
The Reds are now out of the relegation zone when Portsmouth's 10-point deduction is taken into account, defeats for Pompey at Barnsley and Doncaster late on at Leeds making it a good day all round for Cotterill's men.
"It was an important win for us today," he said afterwards. "They are always welcome at any time but I thought we stepped up the tempo in the second half and got what we deserved.
"We have played better and lost games and a week ago we played some really good football and could have beaten Watford 5-0 but had to settle for a 1-1 draw. But results are all important to us.
"It was a nervous, tense game but goals change mindsets and they also change games and today we got them. Our substitutions also worked for us - sometimes they do, sometimes they don't."