Here is a look at the highs and lows of the Italian's three-and-a-half years in charge at the Etihad Stadium.
Galacticos signed In his first summer at City following his appointment in place of Mark Hughes in December 2009, Mancini raided La Liga for the likes of Barcelona's Yaya Toure and Valencia's David Silva and Serie A for Mario Balotelli to drive the team's Premier League title bid.
FA Cup winners City ended their 35-year wait for a major trophy with a 1-0 win over Stoke at Wembley in May 2011. Toure scored the winner 16 minutes from time.
United hit for a six City fans were in dreamland at the home of their greatest rivals in October 2011 as Mancini's side thumped Manchester United 6-1 at Old Trafford. Two goals each from Balotelli and Edin Dzeko and one apiece from Sergio Aguero and Silva hinted at perhaps a changing of the guard in the north-west.
Premier League champions Mancini led City to their first league title in 44 years in one of the most dramatic final days ever witnessed. Trailing 2-1 to QPR and needing to win, Dzeko scored an injury-time equaliser before Aguero grabbed the winner to spark wild celebrations inside the Etihad Stadium. To make it even sweeter, United were the team denied.
New contract Fresh from the title triumph, Mancini signed a new five-year deal last summer.
Tevez on strike Mancini said Carlos Tevez was "finished" at the club after accusing him of refusing to play as a substitute in the Champions League game against Bayern Munich in September 2011. After a disciplinary hearing, fines, a suspension, an unauthorised return to Argentina, appeals, verbal attacks, no transfer and, finally, an apology, Tevez returned to the City fold five months later.
Champions League failure After not making it out of the group in their first season in the Champions League, City failed to even win a game in their six group matches this time around. They picked up just three points to finish bottom of the pool and miss out even on the consolation of a place in the Europa League.
Balotelli bust-ups 'Mad Mario's' talent on the pitch was rivalled only by his ability to create headlines off it. A car crash days after signing, bathroom fireworks, dart throwing and training ground clashes made for an eventful two-and-a-half years before he joined AC Milan in January.
Title surrendered Mancini saw his team surrender their crown meekly back to United, who sealed the return of the trophy in April.
FA Cup upset City, overwhelming favourites against relegation-threatened Wigan, contrived to squander their last remaining chance of silverware this season, with Ben Watson's last-gasp header earning the Latics a deserved and famous victory.