Boundary changes to the electoral divisions, saw an increase in councillors from 45 to 46 and decrease in electoral wards from 42 to 40, took effect at this election after a review of the county by the Local Government Boundary Commission for England.[2][3]
A by-election was held for the Bridport ward of Dorset County Council on 22 February 2018 following the resignation of Liberal Democrat councillor Ros Kayes.[5]