Only a West Brom win at Old Trafford could secure the championship for Pep Guardiola's side this weekend, but a close-range header from Jay Rodriguez in the second half proved enough to end United's slim hopes.
And Mourinho, speaking after the game, insisted he was making no excuses and noted that Man City were deserved champions.
With the title won, City players took to social media to celebrate. Despite the win, West Brom remained in the 20th spot of the EPL table with 24 points. But Mourinho's team produced a stunning comeback to win the game 3-2 and put their rival's celebrations on hold.
Mourinho was hardly effusive in his praise when asked about City's success, but did concede they deserved to be champions. And I know how to win. Sometimes you have to do these sort of things to believe 'wow, we are good too, like the others'.
"I saw lots of people in the moon because we won against City".
"He missed two clear, clear chances against United".
"We did it! An awesome journey to get here". All the lads have done so well and it feels great to be a part of this really special group of players!
"We are delighted to have done so providing our supporters with some very exciting and unforgettable moments".
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It is a great feeling, of course it is a great feeling, but in the end I am just happy to score and help the team. And what a number we scored as a team in the whole season, that's insane .
Also it absolutely was attained by playing a brand of football that has got the purists purring all season with City racking up 93 aims thus significantly and on path to top the 100-point barrier. It's hard to judge Manchester City's exact spot among the Premier League's greatest sides.
City clinched the first division league title in 1936-1937 and 1967-1968, while they have won the competition in its current form twice - in 2011-2012 and 2013-2014.
A serial victor as a manager with Barcelona and Bayern, Guardiola ended his first year in England at City without silverware - his only failure to win a trophy since his managerial career started back in 2007.
City skipper Vincent Kompany has now won three Premier League titles since joining 10 years ago. When you say: "Pep, what you have done in Barcelona or Bayern Munich is it possible to do that without those big players?"
"These players deserve all my respect because they have been unbelievable all season".
They gave a superb response with a swaggering win at fourth-placed Tottenham.
City broke the record for consecutive Premier League wins by winning 18 matches on the trot.
City were knocked out of the Champions League on Tuesday after their quarter-final defeat by Liverpool, and were beaten by League one side Wigan in the fifth round of the FA Cup in February.