Hibs were unable to hold onto Grant Holt's equaliser but it mattered little as a near 20,000 crowd at Easter Road celebrated as they watched Hibs lift the Championship trophy and end a three-year exile from the Premiership.
And Saints, too, had reason for their own party, the Rory Loy goal which cancelled out Holt's 47th minute strike ending all threat of relegation for the Paisley outfit. In the end the Buddies support were chanting "We are staying up," only to be drowned out by the Hibs fans roars of "We are going up."
Hibs should have been ahead within three minutes, John McGinn playing a glorious cross field ball for Holt to head down into the path of Andrew Shinnie. But, with the goal gaping, the midfielder fired wildly over.
Saints, of course, were looking to complete the great escape from the threat of relegation by taking at least a point to ensure safety and they were screaming for a penalty when Hibs skipper David Gray slid in on Lewis Morgan, but referee Alan Muir waved away their claims.
There hadn't been much to get excited about in the first half but it took only two minutes of the second for Hibs to get ahead, Holt stretching out his right foot to direct McGinn's cross from the left beyond Billy O'Brien in the Saints goal.
Saints were needing a goal of their own to avoid the relegation play-off spot and it took a superb block from half-time substitute Jordon Forster to prevent Rory Loy doing just that for the Buddies, the striker then seeing a low shot pushed away for a corner by Hibs goalkeeper Ofir Marciano.
Loy got his reward for persistence on the hour mark, taking Stephen Mallan's pass and sliding a low shot across Marciano and into the far corner of his net.
O'Brien took two attempts to hold Martin Boyle's low shot as Hibs sought to get their noses in front again, the goalkeeper then electing to punch clear Jason Cummings' threatening free-kick. Cummings was looking to add to his 23 goals for the season and he almost did so with a shot on the turn, the ball whistling inches wide with O'Brien a mere onlooker.
Hibs: Marciano, Gray (Forster 46), McGregor, Ambrose, Stevenson, Bartley (Fyvie 46), Boyle, J McGinn, Shinnie (Keatings 76), Cummings, Holt.
Substitutes not used: Laidlaw, Humphrey, Graham, S Martin.
St Mirren: O'Brien, Irvine (Demetriou 43), Baird, McKenzie, Eckersley, Magennis, Mallan, S McGinn, Morgan, Loy (Sutton 88), Smith (Quinn 84).
Substitutes not used: Langfield, Webster, Fjelde, Todd.
Referee: Alan Muir