Two glorious early goals from league player of the season Phil Foden created a party atmosphere in the sunshine at the Etihad Stadium, before a stunning bicycle kick from West Ham's Mohammed Kudus before halftime briefly unnerved the hosts.
But victory never looked in doubt and Rodri sealed the points with a low shot just before the hour from outside the area, giving Pep Guardiola's side a sixth title in seven years.
City now have the chance of winning the double when they face Manchester United in the FA Cup final next Saturday.
Fans danced in their seats, belting out "Champions again!" and "Are you watching Arsenal?" before pouring onto the pitch and setting off blue flares when the final whistle sounded.
In one of the closest title races in Premier League history, Mikel Arteta's Arsenal chased them valiantly and could have taken the championship had City dropped points.
But the Londoners' 2-1 win in their home game against Everton was in vain, leaving them two points behind.
Fantastic Foden
Foden's already brilliant season got even better when he arrowed the ball into the top corner in the second minute then capped a fine team move to sweep home the second in the 18th.
"It's so hard to put into words what we've done today," Foden said. "No team has ever done it. You see what it means to the fans and it means to us. Working all year for this moment.
"I thought today we just looked confident and just played our football and in the end it paid off."
The midfielder has scored 19 league goals this season and has won six Premier League titles at just 23, making him one of England's best hopes for this year's Euros in Germany.
At the final whistle, blue-clad fans defied stewards to rush onto the pitch. The players hugged each other and, once again, later danced in triumph together in their dressing room.
City's latest title was won with 91 points, to Arsenal's 89.
On Sunday, they even had the luxury of seeing 27-goal league Golden Boot winner Erling Haaland fluff two close-range chances.
Final flourish
After trailing Liverpool and Arsenal for large periods of the season, City came good in the run-in - as is their custom - winning nine league matches in a row.
Their latest Premier League title followed a crushing Champions League quarter-final defeat on penalties by their Spanish rivals Real Madrid. Last year, City won the treble of Champions League, FA Cup and Premier League.
Guardiola donned a City top, waving to fans and high-fiving staff, as he walked up to receive his medal, followed by the players who lapped up the fans' adoration one-by-one.
"It feels as amazing as the first one," said midfielder Kevin De Bruyne. "We worked so hard for it. It's been a top battle with Arsenal and Liverpool this year. To again be doing something historic is amazing...
"This is one of my most special. I had a tough year, to be out for six months, but to come back."
Bernardo Silva added: "The achievement is unbelievable. Four in a row. We're so, so proud, and so, so happy."
Guardiola is the fourth manager to win six or more English top-flight titles, along with record holder Alex Ferguson (13), George Ramsay and Bob Paisley (both six).
Despite the deserved plaudits earned by City, for many fans of other clubs their dominance is tarnished by Premier League charges over alleged breaches of financial rules during the ownership of billionaire Sheikh Mansour bin Zayed Al Nahyan.
City deny any wrongdoing and are contesting the charges.