AMB Sports & Entertainment – the parent company of Atlanta United – is among the investors teaming up with Cormack and the two clubs have also agreed to launch a new "strategic partnership".

Cormack's cash has been crucial in getting Aberdeen's plans for a new stadium and training base at Kingsford off the ground.

Now the new chairman – whose investment group also includes Tom Crotty and Roger Lee – hopes to lay the foundations that will see Aberdeen re-emerge as a major force in Scotland.

He said: "As an Aberdonian and lifelong Dons fan, I'm honoured and privileged to become chairman of the famous Aberdeen. I'm also pleased to be able to announce a strategic partnership with Atlanta United, details of which will be announced tomorrow, and further investment from myself, Tom and Roger.

"There are some real challenges ahead but with the support of my fellow directors and new investors, along with our fans, we will do our utmost to deliver success.

"The new investment and this partnership with Atlanta will allow us to punch above our weight, aspiring to attain UEFA's top 100 status, and trying to level the playing field against significantly higher income generated by Celtic and Rangers."

The boardroom change brings an end to Milne's 22-year reign as chairman but he says the time is right to hand over control to his "natural successor".

"For four years, we've been working on a succession plan," said the house building tycoon, who is to remain as a non-executive director.

"It's been no easy task to find the right person who is willing to take on the onerous role of chairman, with responsibility for both the financial health and growth of the club.

"In bringing Dave onto the board and then appointing him vice-chairman, we viewed him as the natural successor.

"He qualifies on both counts. He is prepared to take on the commitment and has already proved his ability to secure significant new investment. Importantly, he is passionate about Aberdeen and the cub.

"I have always said I would relinquish the reins when the right opportunity arose and I believe that time has now come. I'm proud to have had the opportunity to lead the club I love for over two decades."

The club has also confirmed former Scotland boss Craig Brown, along with director Ian Jack, will be stepping down from the board.

Duncan Fraser is also giving up his position as chief executive with immediate effect but will remain as a non-executive director.