Joanna Killian is departing in March for the role of chief executive of the Local Government Association.
The LGA works to promote local government and supports councils to improve.
Surrey County Council says Ms Killian will leave the county in a “robust financial position.”
Tim Oliver, Leader of Surrey County Council, said: “Joanna’s approachable and caring nature, coupled with fierce ambition and sharp knowledge has guided this council through difficult change, tough choices, an unstable economic and political climate, as well as the small matter of a global pandemic – all challenges in which this council has come to the fore, and delivered better outcomes for the residents of Surrey.
“She has kept us true to our ambition that no one in Surrey should be left behind, and her leadership has had a hugely positive impact on this county as a place, and its people.”
Joanna Killian said: “While I’m hugely excited and honoured to be taking up the Chief Executive role at the Local Government Association, it is with a heavy heart that I’m saying goodbye to Surrey.
“Surrey is a wonderful county, full of innovation and ambition, and the County Council reflects that, with a great workforce all dedicated to improving people’s lives.
“Local government plays a vital role in communities up and down the UK, making a real difference every single day. It’s a sector I feel very privileged to work in, and I’m glad to be continuing that journey with the LGA, acting as a strong voice for councils with some big challenges ahead.”