Jamie Paterson scored his first City goal against his former club to help his new employers chalk up a fourth straight victory in all competitions.
Trailing to Apostolos Vellios’ first-half strike, a double change at the interval helped turn the tide in favour of the hosts.
Tammy Abraham capitalised on an underhit backpass to equalise with his 11th goal of the season before Paterson struck the winner just three minutes later.
Lee Johnson made four changes to his side following a hard-fought 1-0 win over Leeds United in midweek.
Taylor Moore, Scott Golbourne, Josh Brownhill and Callum O’Dowda all came into the starting line-up, with Lee Tomlin (suspended) and Mark Little (hamstring) both unavailable, and Joe Bryan and Luke Freeman among the substitutes.
It would take time for either team to create a notable chance. City looked the superior outfit, producing some intricate build-up play in the final third, but clear sights of goal were proving few and far between.
Brownhill looked to take advantage of some good work from Abraham with his back to goal, but the midfielder’s shot from distance deflected behind for a corner.
A clever pass inside the full back from ex-Forest man Paterson then released Golbourne down the left, whose cross definitely struck a trailing arm but the act was deemed unintentional and unavoidable.
Then Bobby Reid got the better of Danny Fox down the City right, only to be hauled down by the left-back. The traditionally unflustered Bristolian took offence to the cynical foul and confronted his opponent, ensuring both men entered the book.
City had certainly made most of the early running, but it was the visitors who made the breakthrough after 33 minutes.
Ben Osborn escaped down the left, latching on to Fox’s lofted pass and reaching the byeline before standing the ball up to the back post.
The onrushing Henri Lansbury got up well to head the ball back across goal and Vellios found the tightest of gaps at the near post to beat the covering Hordur Magnusson on the line with an accurate finish from ten yards.
For all City’s possession, Vladimir Stojkovic remained largely untroubled in the Forest goal. O’Dowda had enjoyed a couple of runs, initially choosing the wrong option after surging into space, before showing great persistence to stay on his feet and produce a cross headed into the keeper’s arms by Reid.
Unusually, a trio of substitutes would enter the field of play at half-time. The visitors made an alteration in defence, introducing Thomas Lam for Damien Perquis, while Johnson made a double change of his own.
Moore and Marlon Pack were the men sacrificed, prompting a tactical switch to 4-4-2 as experienced heads Gary O’Neil and Aaron Wilbraham entered the fray.
Brownhill went to right-back and O’Neil sat at the bottom of a midfield diamond, flanked by Reid and O’Dowda with Paterson at the tip.
The energy of 20-year-old Brownhill in new territory would prove an asset to City. A pacey burst down the right produced a low cross towards Abraham, before the loose ball was struck by Paterson and deflected kindly for Stojkovic.
Reid tried his luck from distance before Magnusson lined up a 20-yard free kick that flew only inches wide as the hosts cranked up the pressure.
It was a level of pressure that soon proved too much for Forest, even if the visitors certainly contributed to their own downfall midway through the second period.
When Lansbury left his backpass short, Abraham was on to it immediately, rounding Stojkovic and slotting home from a tricky angle before celebrating with the home fans.
It had been a long wait to see City score in front of the Atyeo Stand this season, but Ashton Gate had barely paused for breath when Paterson rifled in his first goal for the club three minutes later.
With the ball bouncing around in the Forest box, Abraham kept his head with a cushioned lay-off that Paterson dispatched quite brilliantly with an unerring first-time shot on his left foot that flew into the bottom corner from 15 yards.
It has become a modern day trend for players to avoid celebrating against former clubs, but there was no such thought from the goalscorer, who set off towards the touchline rejoicing in the moment.
City threatened to put the game to bed on the break when Golbourne made good ground down the left and switched the play perfectly for Reid, who took it in his stride and drilled a low shot just a whisker wide at the end of a lung-busting run.
As it was, Forest remained in the game. Aden Flint had to defend manfully, crucially intercepting a cross before just doing enough to put off substitute Nicklas Bendtner, who blazed over the crossbar as a result.
City had got the job done again, extending their winning streak to four ahead of the international break.