Italian businessman Andrea Radrizzani has taken full control of Leeds after buying the remaining 50 percent of shares held by co-owner Massimo Cellino.
Radrizzani, 42, bought a 50 percent stake in the Championship club through his company Aser Group Holding in January and it has been widely reported he had the option of completing a 100 percent takeover at the end of the season if Leeds failed to win promotion.
Radrizzani, who has also become chairman with immediate effect, told the club's official website: "I am delighted to have the opportunity to become a custodian of this great football club.
"The heritage and history of Leeds United attracted me to the club and having spent time at games and at Thorp Arch, I can see that we are ready to move forward to the next level.
"This is a long-term commitment, there is a lot of hard work ahead of us and I am aware of my responsibilities as owner of Leeds United.
"I can assure all supporters that everyone at this club will be doing all we can to build a successful team at Elland Road."
Radrizzani, a sports TV rights entrepreneur who co-founded media agency MP & Silva in 2004, began talks to invest in Leeds in August last year.
He appointed former Real Madrid director of strategy Ivan Bravo to the board at Elland Road in April and his takeover ends the stormy three-year reign of fellow countryman Cellino.
Cellino, 60, who took control at Elland Road in April 2014, sacked six head coaches before appointing Garry Monk last June and had been urged to sell by the majority of fans, who had grown weary of his off-field controversies and handling of the club.
💬 Chairman Andrea Radrizzani discusses building a successful team at Elland Road https://t.co/HX9Kpc4A2f pic.twitter.com/ZV5GM2tF1N
- Leeds United (@LUFC) May 23, 2017
The former Cagliari owner was banned by English football's authorities three times during his tenure at Elland Road.
In February, Cellino announced he would bid to clear his name in the High Court despite an 18-month ban and £250,000 fine for breaching Football Association rules on players' agents being reduced on appeal.
His FA ban and fine, imposed in December 2016 for breaching regulations over the sale of Ross McCormack to Fulham in 2014, was reduced to 12 months and £100,000 respectively.
In April 2014 an independent QC overturned the English Football League's decision to disqualify Cellino due to a tax conviction and the Italian completed his takeover at Leeds having agreed a deal in the January to buy a 75 percent stake from previous owner Gulf Finance House.
But Cellino was disqualified by the EFL for three months in December 2014 after an Italian court confirmed his conviction for tax evasion had been a dishonest act and in October 2015 he appealed against a further EFL ban for another tax conviction in Italy.
Leeds appeared on course to secure a play-off place under Monk this season, but a poor run of results in their last eight games saw them slip out of the top six.
Cellino said: "I have been proud to work at Leeds United, with nice people who have worked at the club with me.
"If you can survive working with me, you can survive anything!
"I have always taught people to work for the club and not for me and in the end the staff have done so in a beautiful way.
"I wish Andrea good luck, I am sure he will continue what I have started and show that people from our country are honest and hard working people.
"Owners come and go but Leeds United will be there forever, for the fans - keep Marching on Together. Goodbye and farewell."