They went into the fixture knowing a win would seal the deal, regardless of what Arsenal did against Everton at the Emirates, with the Gunners sitting two points adrift at the top of the table.
Any nerves at the Etihad were quickly settled as Phil Foden fired City ahead in just the second minute in spectacular fashion. From 25 yards, the England man arrowed a pinpoint drive into the top corner past the despairing dive of Alphonse Areola.
Foden doubled City’s advantage 16 minutes later, turning home Jeremy Doku’s centre, and the Blues were seemingly on their way to a comfortable afternoon.
But Mohammed Kudus’ spectacular overhead kick pulled one back for the Hammers as Takehiro Tomiyasu simultaneously drew Arsenal level against Everton in north London after Idrissa Gueye’s deflected strike had put the Toffees in front.
City didn’t start the second half in the same gusto they did the first, but they did re-establish their two-goal cushion just before the hour mark as Rodri calmly finished from the edge of the box.
Tomas Soucek handled as he scored what would have been a consolation for the Hammers, only for VAR to intervene. Elsewhere, Kai Havertz scored a late winner for Arsenal, but they must settle for second place.
Fans poured on to the pitch at the Etihad after the final whistle, and two-goal hero Foden reflected on his sixth Premier League title at the age of just 23.
“It is so hard to put into words what we’ve done today,” he told Sky Sports. “No team has ever done it [won four in a row], we have put ourselves into the history books. You see what it means to the fans and to us players working all year for this moment. A special moment to share it with the fans.
“I never get bored of it, you want this feeling every time. When you win something there is no better feeling. I want to keep winning as much as I can.”
City have closed out the season in typically ruthless fashion, claiming victory in each of their final nine games of the top-flight campaign.
Following a goalless draw at the Emirates at the end of march, City have been faultless, sweeping all before them to ultimately leapfrog the Gunners at the top of the table.
Arsenal themselves have barely put a foot wrong, but defeat by Aston Villa in north London last month ultimately proved fatal to their hopes of a first title since 2004.
City will now look to add the FA Cup next weekend, as they face Manchester United at Wembley in the final for the second season in a row.