Ipswich Town owner Marcus Evans has sold the League One club to American investment fund ORG.
A new company, Gamechanger 20 Ltd, has been formed to buy the club, with ORG owning a 90% stake.
Americans Brett Johnson, Berke Bakay and Mark Detmer will jointly own 5% of the company, with Evans standing down but still owning the remaining 5%.
Former West Brom chief executive Mike O'Leary will be Ipswich chairman, with a "UK-based" CEO to be appointed.
In a statement, Evans - who owned the Suffolk side for more than 13 years - said ORG "manage funds on behalf of a large US pension fund", with Ed Schwartz acting as their representative on the board.
Johnson, Bakay and Detmer manage the Three Lions fund, and will "oversee and manage the business" alongside O'Leary.
"We are humbled and excited to be investing in Ipswich Town, one of the finest clubs in the history of English football," Johnson said.
"We are committed to restoring Ipswich to its former glory. To this end, the first priority is promotion to the Championship and the management team will be given additional funds to strengthen the playing squad."
FA Cup winners in 1978 and Uefa Cup winners three years later, Ipswich were relegated from the Premier League in 2002 and, after 17 seasons in the Championship, were relegated to the third tier of English football.
They are currently eighth in League One, three points off a play-off place with eight games of the season remaining.
Evans said "a very fair price" has been agreed for his equity in the club and he has waived "much of the club's outstanding debt", meaning "nearly all" of the remaining debt is owed to the new owners.
"I plan to divorce myself from any day-to-day responsibilities and get back to following the Town as a highly interested, passionate and vested fan," he added.
O'Leary said the sale of the club had been discussed for "more than a year", with the Three Lions also part of the ownership group of the American team Phoenix Rising, who play in the USL Championship.
'Evans' reign as owner a failure'
Analysis - BBC Radio Suffolk sports editor Graeme McLoughlin
There were lots of good intentions, and ultimately Marcus Evans kept Ipswich Town afloat by bankrolling the club, but his reign as owner has been one of failure.
A sought-after Roy Keane was brought in as manager and spent big. It didn't work.
Mick McCarthy was arguably a couple of signings away from a promotion-winning side in January 2015. The money didn't come.
Contracts have regularly been run down and a disastrous transfer window in the summer of 2018 was the catalyst to Town playing third-tier football for the first time since 1957.
Major investment is needed to get the club back to where many fans and former players believe it belongs, but a qualified structure within the football management side of the operation is also crucial.
The new owners do have previous experience of running a football club overseas, the question now is can they deliver at Portman Road?