Ms Kerswell has held the role in Northamptonshire since October 2007
The chief executive of Northamptonshire County Council is to leave the post after almost two and a half years.
Katherine Kerswell is to to take the £197,000-a-year group managing director position at Kent County Council.
Leader of the council Jim Harker said he was sorry to see her go and is considering options for future management arrangements.
Ms Kerswell said she is confident the council is well-equipped to meet the challenges Northamptonshire is facing.
In January, she published details of her £197,136 Northamptonshire salary on the council's website and urged others to do the same.