Dave King's application to sit on the Rangers board has been approved by the Scottish Football Association board.
The SFA said it was satisfied that prospective Rangers chairman King was a "fit and proper" person with regards to its rules.
King had to argue his case in light of his previous directorship with oldco Rangers before they went into liquidation and also because of his convictions for tax offences in South Africa.
The Rangers shareholder had swept to power with his allies following a general meeting in early March but delayed taking up an official post at Ibrox until the issue was clarified.
An SFA statement read: "In considering the request, the board of the Scottish FA has sought and received specialist independent legal advice, both in Scotland and South Africa, in respect of Mr King's conviction further to the South African Income Tax Act and in relation to his previous involvement as a director of the club. It has also received significant documentation from relevant authorities both within the UK and South Africa.
"The scale of this due diligence is unprecedented but befitting the complexities of the consideration placed before the board. During this exercise both Mr King and the club were fully co-operative and responded to all questions put to them by the Scottish FA.
"On the basis of this advice presented to it, and having considered all submissions received from Mr King and the club in respect of this matter, the Scottish FA board granted an approval, conditional upon further submissions from Mr King in respect of documented agreements with the appropriate authorities in South Africa.
"The Scottish FA can confirm it has now received this supplementary documentation in full and the board is satisfied Mr King is Fit and Proper in terms of Article 10.2."
A "delighted" King promised to turn his attention "fully to the task of rebuilding Rangers."
He said in a statement: "The Scottish FA's process has understandably been a long one given their recent negative experience with some of the previous board members, who were tasked with being custodians of the club.
"It was essential that I dealt fully with all of the Scottish FA's questions and provided them with everything they required, no matter how personal, in order to prove that there were no barriers to me joining the board of Rangers International Football Club plc.
"I always maintained I would meet the fit and proper requirements of the Scottish FA once they had examined all the evidence and that is what happened.
"I said before that I must be the most scrutinised candidate in Scottish football history, but, as I also previously explained, I was happy to accept this given the importance to the club of having a board fully comprised of individuals with the club's best interests at heart and who are all approved by the Scottish FA.
"We finally have that and my colleagues on the board and I look forward to serving the club in the years to come."
King will outline his plan to move Rangers on from the financial problems that have dogged them in recent years, but his initial focus will be their Scottish Premiership playoff clash with Hibernian.
"I thank the Scottish FA for their diligence in this matter and now it is time to look ahead and map out Rangers' future," he said.
"However, I will elaborate on that in the coming days because there should be no distractions ahead of tomorrow night's match at Ibrox.
"This first leg of the playoff semifinal is absolutely crucial. I will be going to the match and I urge as many Rangers fans as possible to buy the remaining tickets to ensure a packed Ibrox. Together we can help drive the team forward."