Chris Coleman has been “released from his contract” as Sunderland manager, while owner Ellis Short has confirmed he has agreed a deal to sell the club.
An “international consortium of football investors”, led by Eastleigh chairman Stewart Donald, will take over Sunderland subject to EFL approval.
The Black Cats were relegated to League One after losing to Burton on 21 April, their second successive relegation.
Coleman left his job as Wales manager to replace Simon Grayson in November.
The 47-year-old guided his country to the semi-finals at Euro 2016, but is now out of work having won just five of his 29 games in charge at the Stadium of Light.
In a statement, Short said he had paid off all debts owed by the club, leaving them “debt free for the first time since years before” his takeover in 2008.
Sunderland had been listed in Uefa’s annual report as having the 13th highest debt in Europe, more than clubs including Paris St-Germain, Porto and Newcastle.
In February, Short said he would be willing to give the club away for free to a buyer willing to take on the club’s debts.
“For a club with one of the best fanbases, stadium and academies in the UK to find itself in League One is unacceptable,” said Donald.
“We have a carefully thought-through plan to restructure the club, make it sustainable and, with the help of the fans, to restore its sense of pride and reconnect it with the local community.”
Sunderland chief executive Martin Bain last week said “being sold would be a game-changer” and that “it won’t take a lot to make this club great again”.
Short said he had rejected higher offers for the club to sell to Donald, who has since announced he has put Eastleigh up for sale, having owned the club though his company Bridle Insurance since November 2011.
“It is an emotional decision for me and one that I did not expect to have to make,” said Donald, who has invested ÂŁ10m in the Spitfires. “The football club is in the strongest financial position it has ever been in.
“While I have been unable to deliver League football, I hope the fans will reflect on my chairmanship as a positive one.”
Eastleigh were promoted to the National League for the first time in their history in 2014 but have been unable to reach the English Football League – despite Donald’s attempts to “buy his way out” of the division.
Donald has overseen numerous managerial comings and goings during his time as owner, with current boss Andy Hessenthaler their fifth different full-time manager since Richard Hill’s departure in 2015.
The club’s National League campaign came to an end on Saturday, as the Spitfires finished the season 14th in the table.
Former Fulham and Coventry City manager Coleman is the 10th permanent manager to leave the Wearsiders since Roy Keane’s exit in December 2008.
Following the defeat by Burton, Coleman told BBC Newcastle that he hoped to remain in charge of Sunderland next season.
“I know what needs to be done and I hope I get the chance to do it,” he said.
“I came to manage Sunderland, it’s a great club and we’re in tough times and what’s happening around the corner I have no idea.”
Coleman’s assistant Kit Symons has also left, with the club not revealing who will lead the team for their final game of the season against champions Wolves.
Andrew Cole, Former England, Sunderland and Manchester United striker on BBC MOTD2 Extra
“Everything is a short-term fix at Sunderland. I’m not sure what they expected of Chris Coleman when he took over before Christmas.
“He’s had a lot of young players, a lot of loanees and they’re in a relegation battle.
“What were they expecting from him? I’m really disappointed that he’s lost his job.”