Although the takeover is subject to shareholder approval at an extraordinary general meeting on December 14, the club confirmed on their website that there had already been irrevocable undertakings from 43.6 percent of the company's shareholders to vote in favour of the deal.
Mandaric, formerly at Portsmouth, will step down from his duties at Leicester later on Monday having after selling that club to Asia Football Investments.
Mandaric's UK Football Investments group will pay one pound to acquire the club having agreed to pay off a debt of 300,000 pounds which is the subject of a winding up order, brought by HMRC and due to be heard in the High Court on December 1.
The new Board will consist of Mandaric as chairman and directors Howard Wilkinson and Nick Parker.
"Sheffield Wednesday is one of the most famous names in football. I have been able to speak to a lot of people in and around the club in recent weeks, and their passion for Sheffield Wednesday has helped inspire me to get to this point," Mandaric said.
Wednesday, formed in 1867, are currently fourth in League One after they were relegated from the Championship last season.
The Yorkshire club, who are four times English champions and three times FA Cup winners, were founder members of the Premier League and remained there until they were relegated in 2000.
