Ken Powell will retire as chairman of the board at General Mills at the end of this year, completing the transition of power to Jeff Harmening, who became chief executive in June.

The board elected Harmening to take over the chairmanship when Powell retires on Jan. 1. Harmening will continue in his role as chief executive.

Powell, who became chairman and chief executive of General Mills in 2007, maintained his position as board chair during the leadership-transition period, but his full retirement was expected.

"[This] concludes a long and thoughtful process of leadership transition by the board of directors," Kerry Clark, independent lead director of the General Mills Board, said in a statement. "We are very supportive of Jeff's leadership efforts on behalf of the company since his appointment as CEO."

Under Harmening's watch, General Mills restructured its global leadership team into four business units that report directly to the CEO.

The reorganization was meant to improve communication companywide with an eye toward agility and quickening reaction time.

"Jeff is leading the company through significant changes with a steady and thoughtful hand, and it is exciting to see the speed in which the teams are responding," Powell said in the statement.