Woodley and Derek Simpson — with whom he has shared the leadership position since 2005 — are stepping down following the election of Len McCluskey in November.
Union rules stipulate that Woodley could stay on as joint head for another year, but Woodley has decided to relinquish leadership, saying: "I cannot be persuaded that is a sensible course of action – it is not in the best interests of the union, or of Len himself, to have another twelve months of two-headed direction of Unite."
The two joint general secretaries have been in power since the formation of Unite by the merger of the Transport and General Workers’ Union and Amicus.
Woodley will now act as the union’s executive officer for organising.
Commenting on the move, McCuskey said Woodley would help Unite "deliver on its pledge to stop the most vicious attacks on the lives of working people for generations."
"It was not be easy for him to make this decision but it is testimony to Tony that he believes that to do so is in the best interests of our union," McCuskey said.