Ruth Dombey was revealed as the new leader of Sutton Council last night.
Councillor Dombey, current deputy leader of the council, will take over from Sean Brennan when he steps down from his role later this month.
Coun Brennan, who has been leader of Sutton Council since 2002, announced Coun Dombey as his successor at a full meeting of the council last night.
He said: "It will come as no surprise that councillor Ruth Dombey is my successor.
"The times ahead will be demanding and challenging, but I'm confident our new leadership team will rise to the challenges as and when they arise."
She was elected by the Liberal Democrat Group on Sutton Council, but will not take up the role until later this month.
Who will join Coun Dombey on the Liberal Democrat's frontbench is still unclear.
Several roles previously assigned to council cabinet members are to be axed when a new committee system is formally adopted on May 21.
Coun Brennan was also revealed as Sutton's new mayor last night, with councillor Joyce Melican becoming deputy mayor.
They will be formally appointed to the positions at the annual council meeting on Monday, May 21.
Coun Brennan, a former teacher who has lived in the borough for 34 years, first became a councillor in 1986.
He represents the Sutton Central ward and served a term as mayor in 1990.
It is rumoured he may be nominated for a future role in the House of Lords.