Celtic 2 - 0 Hearts: Champions become '˜The Invincibles'
Griffiths kick-started the title party five minutes after the interval when he headed home a cross from the impressive Patrick Roberts.
Brendan Rodgers’ side made it a 34th win of the league season on a day of celebration at Celtic Park before, during and after the 90 minutes.
As both teams came out, the home fans produced a stadium-wide display in tribute to their European Cup-winning team ahead of next Wednesday’s 50th anniversary which included an image of the trophy and a giant ‘Lisbon Lions’.
With the trophy presentation to follow after the game, a sold-out home crowd were made to wait for their first celebration of the day.
Celtic, who had Cristian Gamboa in for Mikael Lustig, were restricted to long-range shots in the opening quarter with Kieran Tierney, Griffiths and Callum McGregor all coming close.
Hearts, who handed 19-year-old Jamie Brandon a debut at wing-back, also threatened from free-kicks by Alex Tziolis and Bjorn Johnsen, who retained his place after head coach Ian Cathro played down reports of a bust-up with the striker at half-time during their midweek defeat by St Johnstone.
Celtic upped the tempo towards the end of the half but Viktor Noring made a good stop from Dedryck Boyata after a Griffiths corner and Hearts managed to clear after Roberts had turned Aaron Hughes inside and out before firing the ball across the face of goal.
Tom Rogic came on for Gamboa at half-time as Celtic moved to a three-man defence and the extra midfielder quickly made a difference.
Roberts got outside Liam Smith and delivered a right-footed cross for Griffiths to head home from six yards.
The goalscorer came close again after linking up with the same player and Scott Brown hit the outside of the post as Celtic kept up the pressure.
Griffiths turned provider when he got clear down the right and delivered a low cross towards Scott Sinclair at the back post. His ball was cut out but Armstrong was following up and shot into the top corner from 12 yards.
Kolo Toure came off the bench for Celtic and produced a goalmouth clearance to deny fellow sub Malaury Martin a goal, before Johnsen headed against the post from the resulting corner.
Hearts continued their late flurry and Craig Gordon saved Martin’s volley at his near post before the whistle blew on an outstanding league campaign for Celtic, who will complete the treble if they beat Aberdeen in Saturday’s William Hill Scottish Cup final.