The owner Ken Bates has been involved in investment negotiations for the last six months.
And GFH Capital — a subsidiary of Bahraini investment bank Gulf Finance House — will complete a 100% takeover after talks lead by Leeds supporter and Deputy CEO David Haigh.
Haigh commented: “After a long process of negotiations, spanning Leeds, London, Monaco, Dubai and Bahrain, it gives us great pride today to have completed the deal for Leeds.
“A brief but important transitional period now begins in terms of the changeover of ownership.
“We have today injected further funds into the club and now we look to the future and start the exciting journey to take Leeds back into a prime position in English football once again.”
GFH Capital’s takeover, thought to have been worth in the region of £52m, should give cash for Neil Warnock — who has lead seven clubs to promotion — to bring in new faces.
Stoke duo Cameron Jerome and Ryan Shotton, as well as QPR defender Clint Hill, have been linked with emergency loan deals ahead of Thursday's 5pm deadline.
Bates, who has been at Leeds since January 2005, will stay on as chairman at Elland Road until the end of the season.
The former Chelsea owner claims he will then move to the role of president.
He said: “I look forward to sitting back and taking more time off.”
Bates was criticised by a section of Leeds fans who feel he has focused finances on non-football matters such as the £6m development of new executive boxes and suites.
During his tenure, the club reached the Championship play-off final in 2006 but went into administration and were relegated to League One a year later.
Bates retained control throughout the crisis, which saw Leeds start the 2007-08 season with minus 15 points.
They spent three seasons in the third tier before manager Simon Grayson led them to promotion in 2010.
But despite having the largest income and some of the biggest crowds in the league, Leeds have struggled to challenge the top of the Championship.
In May last year, Bates bought the club from offshore owners who appointed him as chairman — despite claiming not to know the identity of the group.
Yet star players such as Max Gradel, Jonny Howson and Robert Snodgrass were sold, much to the fury of fans.
Supporters protested against Bates throughout last season and called for a change of ownership with him telling supporters to “put their money where their mouth is”.
An American consortium was linked with a takeover before Leeds confirmed they had agreed an exclusivity period with another group.
The Middle Eastern bid — with members believed to be from Bahrain — looked likely to be completed before the start of the season.
However, on August 9, Leeds said the exclusivity period had ended without a deal being agreed.
Talks continued and GFH Capital’s Haigh, board member Salem Patel and managing director Hisham Alrayes were spotted at matches.
A Companies House document last month revealed the private equity firm had paid £2m for an agreement which prevented other potential bidders buying the club.
Despite a promising start to the season, Leeds have sunk to 18th in the Championship table after a run of seven league matches without a win.