Sunday's 1-0 victory over Chelsea was played out in a party atmosphere after Arsenal's defeat 24 hours earlier at Nottingham Forest handed City the title.
City manager Pep Guardiola left the likes of Erling Haaland (22), Jack Grealish (27), Ilkay Gundogan (32), Rodri (26) and Kevin de Bruyne (31) on the bench but it made no difference as City clamed 12 league wins in a row.
Five league titles in six seasons represents almost total domination, but City's players now have their eyes on sporting immortality by beating Manchester United in the FA Cup final and Inter in the Champions League showpiece.
Should they do that they would match United's unique Premier League/FA Cup/Champions League treble of the 1998-99 campaign.
"We still have a big couple of weeks before we can take our foot off the gas," Walker told Sky Sports as thousands of City fans celebrated on the Etihad Stadium pitch.
"Rest assured we are not finished. We have the FA Cup against our bitter rivals and then the Champions League. We will celebrate tonight and then move on to try and create history.
"The treble would be fantastic but there is a lot of football to be played."
United's treble-winning captain Roy Keane said it was difficult to compare the current City side with the United one he played in under Alex Ferguson.
"I would like to think we would have competed against Manchester City," said the Sky Sports pundit.
"They are a brilliant team. They have great pride in their defending, a great goalkeeper (Ederson). They are on the verge of greatness and we will see in the next couple of weeks."
