Roberto Mancini's men flew out of the blocks and took the lead after just seven minutes. Rovers 'keeper Paul Robinson fumbled a Martin Petrov corner, the ball fell to Benjani, whose scrambled cross-shot was forced over the line by Tevez for his eighth goal in seven games.
Blackburn recovered from that early setback and settled into the match but couldn't carve out any decent chances, with long-range efforts from Steven N'Zonzi and Gael Givet the sum total of their attacking threat in the first period.
The game looked to be drifting towards the break before City scored a wonderful second. Micah Richards burst over the halfway line and ran right through the heart of the Rovers defence before laying the ball off to Benjani. His shot came off the post but Richards was on hand to finish off the move he started to put City in complete control.
Rovers boss Sam Allardyce made two substitutions at half-time in a bid to get back into the game but they instead found themselves further behind within four minutes of the re-start.
Benjani did well down the right and laid the ball off to Tevez on the edge of the area who fired the ball home first-time past Robinson.
The game looked over before Rovers got back into things with 19 minutes left. Vincent Kompany mis-controlled Shay Given's pass and let in Morten Gamst Pedersen who curled the ball into the far corner.
Record-signing Robinho came off the bench soon after and made an immediate impact, first having a goal ruled out for offside and then drawing a good save out of Paul Robinson as City looked to finish the game off.
But it was Tevez who saved the best till last in stoppage time, cutting inside three Blackburn players and curling the ball into the top corner from 25 yards to complete a marvellous hat-trick and a empathic fourth win in a row for Roberto Mancini's men.