Roberto Mancini's men scored twice in added time to beat QPR 3-2 and win the club's first title since 1968 on a day of incredible drama in the Premier League.
Roberto Mancini's men led at halftime when Rangers goalkeeper Paddy Kenny failed to stop Pablo Zabaleta's snap-shot from six yards after 39 minutes.
But, with Mark Hughes' side camped inside its own half for the majority, Djibril Cisse pounced on a mistake by Joleon Lescott to hammer an equalizer past Joe Hart.
City appeared to be handed the upperhand when Rs' captain Joey Barton was sent off just before the hour mark for striking Carlos Tevez, only for QPR to go in front when second-half substitute Armand Traore stormed down the left flank and delivered a whipped cross for Jamie Mackie to head into the net.
As the game entered stoppage time, Edin Dzeko lost his marker at a corner to equalize, with Sergio Aguero scoring the most dramatic of winners with just one minute of playing time remaining.
A first-half Wayne Rooney header was enough for the Red Devils to claim the three points needed over Sunderland, but Sir Alex Ferguson's side needed Manchester City to slip up against QPR if it was to claim the team's 20th league title.