The deal sees GFH Capital Limited, which has financially supported the club since entering into an exclusivity period, injecting further funds and helping to strengthen the team.
GFH Capital executive David Haigh will join the board immediately, with GFH Capital executives Hisham Alrayes and Salem Patel joining in December.
Ken Bates will remain as Chairman for a transition period until the end of the season, after which a new chairman will take over. Bates will become club President.
"I can confirm we have now completed all the negotiations with GFH Capital. We have completed the first part of the purchase and they will be taking over 100 per cent of the club. Meanwhile, there is a transitional period while they get to know more about the club.
"I will continue as chairman until the end of the season when I will take over as president and I look forward to sitting back and taking more time off. Neil Warnock will continue as manager and we look forward to a smooth transition.
– Ken Bates, Leeds United chairman
"One thing I can say that has benefited from the negotiations is that this six-month courtship has given GFH Capital the opportunity to see the strengths and weaknesses and what needs to be supported. You can look forward to a smoother transition than we've seen at a lot of clubs.
"I'd like to thank, on behalf of Susannah and myself, the tremendous support we have received over the years, particularly over the last 12 to 18 months which hasn't been easy, but has made us more determined to see the job through."