In a dramatic and nerve-wrenching climax to the season at Celtic Park, Hearts, with their Australian midfielder Devlin playing a key role in midfield, had been closing in on a first title for 60 years as the sides were locked at 1-1, a draw being enough for the Edinburgh visitors.
But Daizen Maeda and Callum Osmand ended up scoring the late goals that earned Celtic their record 56th Scottish title and ensured the 41-year-old duopoly of Celtic and Rangers 'Old Firm' title domination continues.
When Osmand struck with virtually the last kick of stoppage time, chaos ensued with delirious Celtic fans streaming on to the pitch after a week in which the title race drama had dominated the national news in Scotland.
In a dramatic finale, Celtic piled forward to try to find a winner with the scores level, and it looked as if they might miss out as Kelechi Iheanacho hit the post.
Even when Maeda scored the decisive goal from close range in the 87th minute, it looked like heartbreak for Celtic as the offside flag went up.
But just as in midweek when Celtic were rescued by VAR with the award of a late penalty that enabled them to beat Motherwell, an agonising wait finally ended with the goal being allowed to stand on review.
Hearts, who'd led the table for 226 days since October, tried to respond in stoppage time, and sent everyone forward for a final corner, but when it broke down with the Jambos' keeper Alexander Schwolow stranded, Osmand broke away and went half the length of the pitch to slot into an empty net.
It was the ultimate misery for Hearts, who'd been on their way to glory when their inspirational captain Lawrence Shankland headed them in front from a corner in the 43rd minute.
But Celtic were level before halftime, again aided by VAR when Alexandros Kyziridis was judged to have blocked a Tierney cross with his arm and Arne Engels scored from the penalty spot.
There was nothing but despair for the 27-year-old World Cup-bound Devlin, who's played a huge part in Hearts' breakthrough season but whose future at the club after five years is uncertain as his contract's up. His family had all flown in from Australia to watch his big moment.
But for 74-year-old Martin O'Neill, who'd guided Celtic to a fourth title after being persuaded out of retirement to manage the club again amid an early-season slump, there was nothing but joy.
"The players, the coaching staff have given me a reason to live - that's not to say my family haven't! - but this is the most special place on earth," he told his adoring supporters.
"When there is absolute unison in this stadium, it's a sight to behold. The players have been absolutely magnificent."
