Jack Grealish’s late goal denied Brighton the title as David Stockdale’s mistake handed the Sky Bet Championship crown to Newcastle.
The goalkeeper failed to deal with Grealish’s 89th-minute effort as the Seagulls were held to a 1-1 draw by 10-man Aston Villa.
Newcastle beat Barnsley 3-0 to take the title by a point despite Glenn Murray’s second-half penalty putting Brighton on the brink at Villa Park.
Nathan Baker was sent off after bringing down Sam Baldock for the spot kick but Brighton could not capitalise.
The Seagulls were already promoted, ending a 34-year top-flight exile, and victory would have seen them go up as champions but they lacked urgency and rhythm for long spells.
Chris Hughton’s side rode their luck in the first half and Henri Lansbury wasted a glorious Villa chance as the hosts finished a disappointing season 13th with boss Steve Bruce needing to revamp his squad in the summer.
Villa, relegated last year, had long hoped there would be a promotion party in Birmingham but it was the visitors who were celebrating going up – even if they struggled to get going.
Lansbury’s low effort was shovelled wide by Stockdale during a low key start.
It was competitive enough but there was little action until Lansbury somehow managed to head wide from five yards after Sebastien Pocognoli chested the ball into his path.
Premier League-bound Brighton seemed too relaxed over their title chase and needed Stockdale to bail them out after another Pocognoli error after 33 minutes.
The on-loan West Brom defender played a blind backpass to slip in Scott Hogan but Stockdale deflected his shot wide and the goalkeeper was then needed again to save Conor Hourihane’s free kick.
There was little on offer from the Seagulls and they survived a huge penalty scare five minutes after the re-start after Lewis Dunk tackled Keinan Davis but referee Darren Bond waved Villa’s protests away.
But the visitors suddenly woke up as Murray headed wide and then Baldock forced Sam Johnstone into a smart save just before the hour.
And the title swung Brighton’s way when they went ahead after 64 minutes.
Murray slipped in Baldock and he managed to scuff an effort at Johnstone, only for referee Bond to rule Baker had fouled him before he got his shot away
The defender was sent off and Murray scored his 23rd goal of the season from the spot.
Four minutes later Brighton should have doubled their lead when James Chester blocked Baldock’s effort following Tommy Elphick’s short backpass.
But while it remained 1-0 there was always a chance the Seagulls could lose the title and Stockdale had to produce a fine stop from Hourihane’s free kick with five minutes left.
However, the 31-year-old then cost his side the league crown when he allowed Grealish’s low 25-yard effort to sneak in with a minute left.