he “had failed to achieve any of the club’s targets, with the exception of qualification for next season’s Champions League”.
Assistant Brian Kidd will take charge for the final two games of the season and a tour to America in late May.
Malaga’s Chilean coach Manuel Pellegrini has been strongly tipped to replace Mancini.
On Sunday night, 59-year-old Pellegrini, who spent one season in charge at Real Madrid in 2009-10, insisted there was no deal in place for him to become the new City boss.
“I deny here and now being the new coach of Manchester City,” he said after Malaga’s goalless Primera Division draw with Sevilla. “I haven’t signed any agreement with anybody.”
In a statement, City thanked 48-year-old Mancini for the job he had done since joining the club in December 2009.
But the club said the failure to hit “stated targets” and the need to “develop a holistic approach to all aspects of football at the club”
“Roberto’s record speaks for itself, he secured the love and respect of fans,” said chairman Khaldoon Al Mubarak. “He has done as he promised and delivered silverware and success.”
City added it was “a difficult decision” to part with Mancini, explaining it was “the outcome of a planned end of season review process that has been brought forward in light of recent speculation”.
A replacement for Mark Hughes, Italian Mancini was in charge for three-and-a-half years, winning the FA Cup in 2011 and City’s first top-flight league title for 44 years in 2012 – a year to the day before his sacking.
In July 2012, he signed a new five-year deal with the club.
But this term, City are a distant second to champions Manchester United, went out of the Champions League in the group stages and lost the FA Cup final to Wigan.
Mancini was critical of Manchester City officials for failing to deny the newspaper reports that surfaced on the morning of Saturday’s FA Cup final stating he would be sacked and replaced by Pellegrini.
City were beaten by Ben Watson’s 90th-minute header at Wembley as Wigan, struggling to avoid relegation from the Premier League in 18th place, became the lowest-ranked team to win the FA Cup since West Ham in 1980.
City thrashed rivals United 6-1 at Old Trafford in October 2011 en route to their first Premier League title and beat them again on their home ground this season.
But Sir Alex Ferguson’s team wrapped up their 20th league crown last month with four matches remaining.
Mancini’s record in the Champions League has come under particular scrutiny.
He reached the quarter-finals with Inter Milan, but City have been eliminated in the group stages of both their campaigns during his reign.
Having finished third in their group last season, behind Bayern Munich and Napoli, they again failed to qualify for the knockout stages this term.
They failed to win any of their six matches in a formidable group that also contained Borussia Dortmund, Real Madrid and Ajax.
Their tally of three points was the lowest by an English side in the group stage of the competition.
City have two games remaining in the Premier League this season.
They face Reading at the Madejski Stadium on Tuesday before finishing their campaign at home to Norwich on Sunday and then travelling to America to play Chelsea in St Louis on Thursday 23 May and New York on Saturday 25 May.