City had moved to the brink of glory with victory at Tottenham on Saturday but the crowning moment came in unexpected circumstances as Jay Rodriguez headed the bottom side to a 1-0 win at Old Trafford.
That prompted jubilation in the blue half of Manchester and a group of players including captain Vincent Kompany, Bernardo Silva, Kyle Walker, Fabian Delph and John Stones partied in public at a bar in Hale, near Altincham.
Earlier, Kompany had been watching United’s game in the presence of TV cameras and he was quick to set his team-mates the target of retaining the title next season.
“I suppose my team-mates will roll their eyes a little bit but I kind of want to see what the reaction is now,” the Belgian, also a title-winner in 2012 and 2014, told Sky Sports. “I have never retained a title so I want to see if this team’s got it to carry on and be even more successful.”
Kompany said he shared that ambition with manager Pep Guardiola, who has now won 23 major trophies in a glittering managerial career that has included glorious spells at Barcelona and Bayern Munich.
“I think we share one thing maybe, the hunger and desire to never be satisfied,” said Kompany.
“This is not a dynasty, it is one title we’ve won. We’re still super happy but there’s is so much to do before we unlock our full potential.”
Guardiola himself had said he would not be watching the United game and instead played golf with world number 12 Tommy Fleetwood at Sandiway Golf Club in Northwich, Cheshire.
Yet, knowing the job was almost done, he gave his players a ringing endorsement after they returned to their best with a superb 3-1 win over Spurs at Wembley on Saturday.
City had lost their previous three games to slip out of the Champions League to Liverpool and miss an early opportunity to wrap up the title against United.
“It’s incredible the way we played and I am so glad to be here and be part of this club,” Guardiola said. “These guys are fantastic, awesome – they are incredible. This club is absolutely amazing in all terms.”
With the title won while City were not on the pitch, they will not get the chance to celebrate the win fully with fans until they return to action against Swansea at the Etihad Stadium next Sunday.
City lost three successive games in which they were dumped out of the Champions League by Liverpool and missed out on the chance to seal title glory against rivals Manchester United.
They eventually got the job done this weekend, though, as a scintillating 3-1 win at Tottenham on Saturday put the champagne on ice and the corks were popped less than 24 hours later when Manchester United surprisingly lost at home to West Brom on Sunday.
To come through the other side of a tough week in such fashion was a big tick for City, who won at Wembley thanks to goals from Gabriel Jesus, Ilkay Gundogan and Raheem Sterling.
The full-back said: “That’s the most pleasing thing about it. We’ve had probably the toughest period, definitely in my career at the club.
“We’ve gone from doing so well in all competitions to take three losses, and sometimes it felt like it was a relegation battle in there with the mood.
“We’re all winners and we want to win and in those games unfortunately we didn’t. But we put that right.
“That shows the character and the belief in the standard of players in the dressing room.”
City have unquestionably been the best team in England but their status has been undermined by their Champions League exit.
And while Walker admits to wanting Liverpool to win the competition, he is gutted City will not get the chance.
“I’m not going to stand here and say we didn’t deserve what happened,” he added.
“Liverpool beat us in two games and congratulations to them. I wish them all the success in the Champions League because it would be fantastic for an English club to go and win.
“I’ve got a bitter taste in my mouth that it isn’t us but you have to take your hat off to them. They beat us over the two games and that’s all you can say.”
It was a first return to Walker’s former club since a summer switch to City and he was given an unfavourable reception by the fans, who booed him.
The 27-year-old stands by his decision to leave Spurs, but is still tipping them for a brighter future.
We did it! An amazing 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! Thank you for your support all season! #sharkteam🦈 @mancity pic.twitter.com/Bpezwwn4UE— Kyle Walker (@kylewalker2) 15 April 2018
He said: “We won the Carabao Cup and that was a step in the right direction for me but to be competing in the Premier League since I was 19 and to play all the games I played in the Premier League, to not win the Premier League, it was a bit devastating for me not to have won it with Tottenham.
“So to come here and win in my first season, it’s fantastic for me.
“You always say is the grass greener on the other side, and it looks it.
“Whatever you read, I know what really happened. I know the truth behind it and so does the Tottenham boss.
“But I won’t stand here and start slagging people off because that’s not what I’m about.
“I left because it was a time in my career that I needed to move on. And luckily it’s worked out.”
Mourinho’s second-placed United slipped to a shock 1-0 loss to bottom side West Brom on Sunday, a result that put runaway leaders City out of reach.
The United manager said: “I knew that sooner or later that (they) would be (champions) and if I was in their position I would be very upset if somebody said that they won the title because Manchester United lost against West Bromwich Albion.
“They won the title because they were the best team, because they won a great amount of points. They lost only two matches because they were the best team. That’s the reason why they were champions.”
United delayed City’s title celebrations by winning last week’s derby at the Etihad Stadium but Mourinho admitted that victory had a hollow feel.
He said: “Probably because I (have) won eight championships I was not in the moon with the victory against them, because that doesn’t make me feel super happy.”
Mourinho suggested he had already congratulated his rivals in advance.
He said: “I don’t know if I was the first or if I was the second or the third, but I congratulated them face-to-face when I had the chance to do it.”
United produced a subdued performance against the Baggies and were beaten by a 73rd-minute header from Jay Rodriguez.
Congratulations to Manchester City on their Premier League title win.— Manchester United (@ManUtd) April 15, 2018
Mourinho said: “We were masters in complicated football, everything was complicated.
“We couldn’t play fast, we couldn’t think fast, everything was complicated.
“They always had time to organise themselves.
“Probably in our best period, where we were moving the ball better and the team was thinking faster, they scored the goal in the only way they could score a goal, which was in a corner or in a lateral free-kick. After that they closed every door.”
West Brom remain nine points adrift of safety with just four games remaining and seem unlikely to stave off relegation, but caretaker boss Darren Moore was pleased with their efforts.
Moore said: “It was a good performance today and we got our just rewards in the end. We have come up against a very, very good side in Manchester United but everyone stuck to their job and did everything we asked of them.
“In the end, when the ball did break for us, we used it well at times and created chances in open play and then got the goal. It stops the rot.”