Leeds United and Southampton will now both compete in the play-offs for a place in the Premier League
Leeds will play Norwich City in the Championship play-offs and Southampton will take on West Brom after the Saints claimed a deserved win at Elland Road.
The third-placed Whites went into the game knowing they had to win and Ipswich lose to all-but relegated Huddersfield to secure automatic promotion.
But the Tractor Boys' victory the Terriers means both these sides must go through the play-offs to return to the Premier League.
The visitors went in front when Adam Armstrong confidently converted Che Adams' low cross first time but Leeds quickly levelled through Joel Piroe's thumping finish from the edge of the area.
Will Smallbone put the away side back in front after superb play by Kyle Walker-Peters to keep the ball in down their right and then tee him up with a measured pass.
Southampton came into the game on the back of three straight losses but were good value for their first win here in West Yorkshire since March 2012.
This victory completed the double for Russell Martin's men against Daniel Farke's side, in what could potentially be a dress rehearsal for the Championship play-off final on Sunday, 26 May.
Ipswich's success means that once again all three teams relegated from the Premier League will not be going straight back up at the first time of asking, with one of these pair bound for another campaign in the EFL.
Whites slump into play-offs
Just a few weeks ago this match had looked like it could potentially be a decider for an automatic promotion spot for either side.
However, Saints slipped to three defeats and Leeds lost at home for the first time against Blackburn three weeks ago before being battered 4-0 at QPR last Friday to go into today's game in need of a miracle.
Despite their indifferent form and things not being in their hands the game started in a terrific atmosphere with the home side searching for an early goal to put some pressure on their promotion rivals down in Suffolk.
Southampton carried a threat on the break though and took the lead when Adams picked up the ball 20 yards out after a corner and crossed for Armstrong to convert from eight yards.
Leeds quickly levelled though when the away side made a mess of clearing a ball into the middle and Piroe slammed home to give some renewed optimism.
Ipswich soon went in front against Huddersfield at Portman Road and Saints re-took the lead shortly after when Walker-Peters scampered after a deep ball forward from the halfway line and just kept it in, with Leeds full-back Junior Firpo thinking it would go out, before laying it on a plate for Smallbone to score from close in.
Taylor Harwood-Bellis saw a header skim the top of the bar for the away side and Willy Gnonto dragged a low shot just wide for the home side as the open nature of the game continued up to the break.
After the interval the intensity dropped off, with both teams knowing they have bigger games to come in the coming weeks.
Leeds open their play-off campaign against Farke's former side Norwich at 12:00 BST on Sunday, with Saints travelling to The Hawthorns at 14:15 BST that day.
The Whites are looking to go up through the play-offs for the first time at the sixth time of asking, while Southampton have had one unsuccessful play-off campaign before.
Post-match reaction
Leeds boss Daniel Farke told BBC Radio Leeds:
"Today we chose a risky approach because there was no option but to win. It was a bit of a wild game. We wanted an early goal to put pressure on Portman Road.
"The problem was more or less the opponent was in the lead for the majority of the game. I would have liked to have equalised or turned it around for the confidence but I was pleased with the performance in the second half.
"This season is over and you have to say congratulations to Leicester and Ipswich. They were the two best teams in terms of consistency and we were the third best."
Southampton boss Russell Martin:
"I really enjoyed much of the performance. We showed both sides of the game today. We asked for big energy and more aggression and we got that. I'm proud of the players.
"I changed the shape because I thought it suited the game today and it might be something we use going forward in the play-offs. It wasn't negative to start with so many defensive players on the pitch. They were brave.
"It doesn't mean anything that we're unbeaten against all the other teams in the play-offs. It's a totally different competition. We need to be ready. They trained like beasts this week and they'll need to do that in the next two weeks too."
