However, a side showing 10 changes could not see off the Foxes, who took an early lead through a fine volley from teenager Luke Thomas which was cancelled out by Mason Greenwood’s neat finish.
Caglar Soyuncu headed in a corner midway through the second half to secure all three points, which left City as champions with three games still to play.
“This has been a season and a Premier League title like no other. This was the hardest one,” said Guardiola, whose side beat Tottenham at Wembley to win the Carabao Cup final last month.
“We will always remember this season for the way that we won. I am so proud to be the manager here and of this group of players.