The first elections to the council were held in 1973, initially operating as a shadow authority prior to the district coming into effect the following year.
A by-election was held in Melbombe Regis ward on 16 May 2013 following the death of councillor Peter Farrell (Conservative) in April 2013.
A by-election was held in Westham East ward on 4 May 2017 following the resignation of councillor Sally Maslin (Liberal Democrats).
[25] A by-election was held in Tophill East ward on 8 February 2018 following the resignation of councillor David Hawkins (Independent).
[26] Green councillor Claudia Moore (Weymouth West, elected as a Conservative) resigned from the council on 20 December 2017.