The Ibrox club emerged into the Irn-Bru Third Division last summer after descending into administration and liquidation, which effectively rendered the SPL title race little more than a procession for the Hoops.
In the event, there were ups and downs this season before Lennon's side retained the title with a 4-1 win against Inverness three weeks ago.
The Parkhead club confirmed their superiority against Saints with goals from Joe Ledley, Charlie Mulgrew, James Forrest, and an own goal from Saints defender Frazer Wright, as attention now turns to the William Hill Scottish Cup final against Hibernian at Hampden Park in a fortnight's time.
"We have proved we are not a flash-in-the-pan team," said the Northern Irishman, who, in his after-match speech to the crowd, referred to Celtic's "unique and unbroken history."
"I know there will be a lot of people out there saying there is no Rangers, it is a one-horse race and in essence there is something to that.
"We are not going to hide away from that but we have a job to do.
"We have a responsibility to keep winning trophies, it is part of the DNA of the club and to do it in a certain way.
"Since the turn of the year the home form has been as good as I've seen in my time here.
"We know we need to tidy up away from home but the league is won now and we can focus on finishing the season with a cup final."
- Sports & Recreation
- Charlie Mulgrew
- Joe Ledley
- James Forrest