In a statement to the Stock Exchange, Rangers announced the 65-year-old would take up the role vacated by Walter Smith three months ago and will lead the hunt for a successor to former chief executive Craig Mather who left on October 16.
Rangers also revealed their long-awaited annual general meeting, scheduled for October 24 but postponed after a group of shareholders succeeded in forcing its postponement, will now be held on December 19.
"The board of Rangers announces that it has appointed David Somers as an independent non-executive director and acting chairman," the club said.
"Mr Somers is an honours economic studies graduate and a qualified accountant (Fellow of the Association of Chartered Certified Accountants).
"He spent all his career in fund management and in addition has considerable experience in matters of corporate governance."
And Somers is keen to get started in the role and insists he will do 'everything in his power to restore the club to its former glories'.
In a statement on Rangers' website, he said: "It is a huge honour and privilege to be appointed acting chairman and non-executive director or Rangers Football Club.
"I know from my visits to Ibrox Stadium - including a number of Champions League games - that the club has a tremendous fan base.
"Ally McCoist has the players performing well on the pitch so my task now is to strengthen the board to the level that Rangers Football Club deserves.
"The 141-year institution is on the road to recovery and I will do everything in my power to help take this great club back to the top of Scottish football where it belongs."