Ross Munro saved a late penalty as Inverness clinched promotion and the William Hill League One title with a 2-1 victory over relegation-threatened Hamilton.
The leaders looked to be finishing in style at the Sarens PSG Stadium on Saturday after a third-minute strike from Daniel Devine and a second goal from Billy McKay.
But Kevin O’Hara set up a tense finish when he pulled one back on 85 minutes and Munro needed to keep out Oli Shaw’s spot-kick in stoppage time to secure the points.
The result meant Caley finished two points above Stenhousemuir while Hamilton’s defeat ended their hopes of avoiding the relegation play-offs.
Stenhousemuir pushed Thistle to the end and wrapped up their regular season campaign with a 2-0 win at Montrose.
Michael Andersen and Olly Whyte were on target either side of half-time but they had to settle for a play-off place.
Queen of the South produced a strong finish to leapfrog Alloa and snatch third place with a 4-1 win at the Indodrill Stadium.
A double from Nicky Clark and a Liam Smith strike in the last 18 minutes sealed victory after Alloa had replied to Brennan Dickenson’s opener through Kalvin Orsi.
East Fife drew 0-0 at Cove Rangers but Hamilton’s defeat meant the Fifers survive in League One for another season.
Rock-bottom Kelty Hearts ended their campaign on a high with a last-gasp 2-0 win at fifth-placed Peterhead. Lewis Moore and Arran Pettifer struck in the final three minutes.
East Kilbride will be playing in League One next season after they thrashed Clyde 5-0 to finish five points clear at the top of League Two.
John Robertson put them on their way after just two minutes before Sam Young’s double made it 3-0 at the break. Jack Leitch and Sean Fagan then struck as Kilby wrapped up their second successive promotion in style.
Second-placed Spartans began the day with an outside chance of finishing top but are heading to the play-offs after drawing 2-2 at Stirling.
Mark Stowe and Steven Lawless put them ahead but Adam Brown and Russell McLean replied.
Bottom side Edinburgh City warmed up for their relegation play-off with a thumping 5-0 win over 10-man Dumbarton.
Divine Iserhienrhien struck early before City took advantage of Kai Kirkpatrick’s sending-off with further goals from Innes Lawson, Dylan Williams, Iserhienrhien and Malek Zaid.
A late goal from Robbie Foster saw Stranraer secure fifth place with a 1-0 win at Elgin while fourth-placed Forfar drew 1-1 at Annan.