Steve Bruce's team were forced to wait an agonising 15 minutes after their 2-2 draw with Cardiff at the KC Stadium to discover their fate with Watford's game delayed due to a serious neck injury to their goalkeeper Jonathan Bond, who replaced first-choice keeper Manuel Almunia before the kickoff.
Watford were drawing 1-1 with Leeds United at Vicarage Road and needed a win to overtake Hull on the final day. But a Leeds counterattack saw Ross McCormack race clear.
The former Rangers striker saw inexperienced Watford substitute goalkeeper Jack Bonham, 19, off his line and attempted to chip him. The teenager, who was making an unexpected debut, could not hold the ball and Leeds won 2-1 and Hull were promoted and Watford left in the playoffs.
At the foot of the Championship table, the movements throughout the game were multifold. Wolves were relegated as they went two down at Brighton, but Peterborough, Barnsley, Huddersfield, Sheffield Wednesday and Millwall were all in danger of joining them.
Yorkshire rivals Huddersfield and Barnsley were drawing 2-2 at the John Smith's Stadium but David Flitcroft's Oakwell side were in the bottom three with Peterborough level with Crystal Palace by the same scoreline.
However, Mile Jedinak headed home a late winner for Palace at Selhurst Park, which meant Peterborough dropped into the relegation zone.
News of that goal filtered through to Huddersfield, where next week's FA Cup Final referee Andre Marriner signalled five minutes of injury time.
However, that produced one of the strangest sights at a football ground this season. With his team safe from the spectre of relegation, Barnsley goalkeeper Luke Steele collected the ball from long punt from the Huddersfield defence.
The 28-year-old, who was born in Peterborough, then refused to pass the ball and simply dribbled with it back and forth across his own penalty area for 80 seconds until Marriner blew his whistle to signal the end of the game.