Neil Lennon's side went into the Glasgow derby clash knowing victory would be enough to land them the SPFL Premiership crown after second-placed Aberdeen could only draw with Ross County on Tuesday.
And the Hoops made no mistake as they eased over the line to retain their title in emphatic fashion, goals from Anthony Stokes (2), Liam Henderson, Stefan Johansen and Kris Commons wrapping up a comprehensive top-flight success.
Lennon's side got off to the perfect start at Firhill when striker Stokes rose well at the back post to head past Paul Gallacher with just two minutes on the clock.
But the Hoops struggled to build on their early lead as Thistle grew into the game in search of an equaliser to give their Premiership survival hopes a massive boost in front of a packed Firhill.
Despite ending the first half positively, the Jags would shoot themselves in the foot just after the restart as Celtic doubled their advantage to take a huge stride towards title glory.
Lennon brought on youngster Henderson for right-back Adam Matthews at the break and the young Hoops star would make an instant impact, showing great composure to fire beyond Gallacher from twelve yards to net his first goal for the club.
Just seconds later, midfielder Johansen made sure there would be no upset as he burst into the box and fired a low shot into the back of the net.
The visitors were twice denied a fourth as Leigh Griffiths saw two strikes ruled out for offside, while Commons somehow put his effort over from a few yards.
Substitute Christie Elliot pulled one back for Thistle late on, but it was Celtic who would have the final say, Stokes blasting home his second of the night and Commons side-footing home a Georgios Samaras pass as Celtic were confirmed champions.
Unfortunately, the lap of honour they were entitled to take was ruined by the idiocy of some of their own support who invaded the pitch at the end.