"So happy to be able to share another trophy with our unbelievable fans", the 32-year-old Belgian defender said on Twitter.
Jose Mourinho's side had prevented their neighbours winning the title with a stirring comeback last weekend, but an unlikely defeat to the Baggies secured a third Premier League title for their cross-city rivals.
City's victory means that none of the last nine Premier League champions have been able to defend their title. Manchester City were crowned Premier League champions on Sunday as Manchester United crashed to a shock 1-0 defeat against West Bromwich Albion.
First came a double-save in the first half as he did well to block Lukaku's shot with his face before quickly denying Sanchez's follow up.
Gabriel Jesus and Raheem Sterling scored for City either side of an Ilkay Gundogan penalty as they bounced back in style from the disappointment of their Champions League quarter-final exit at the hands of Liverpool in midweek. I have been lucky to win three but so many I have missed as well.
'City were the best team, sooner or later they would get the points, so no dramas when the best team wins the league'.
"We've won the league for you, Man City, Man City", West Brom's fans chanted after the final whistle. They were the right ones, and the ones we believed in, I'm sure there are differences to how we play today compared to Bayern [Munich] and Barcelona; we survive and live by the strength of the team.
"We played a bad game this Sunday".
It caps a remarkable Premier League season that has seen City lose just twice thus far and win 28 of their 33 matches with a record-breaking run of 18 successive victories between August and December.
"We did it! An awesome journey to get here".
Some players think it is stylish football, ' he said.
'The commitment, the desire, and I said, "Can Pogba do that all the time the way he played against City?".
City's fans must have been left with soaring hearts on hearing how the Spaniard, in the second of a three-year deal, had talked of his long-term ambitions to make City's name resonate more in global terms.
And though Foster won't be at the World Cup in June, he could yet be in the Premier League with a new club next season.
Despite the win for West Brom the layers remain convinced that they will be relegated to the Championship with no one willing to offer the minimum odds of [1.01] in the Relegation market.