On 24 May 2018, a by-election was held in Westbury-on-Trym and Henleaze ward, resulting in the Conservatives gaining a seat from the Liberal Democrats.

[5] On 22 March 2019, the Eastville councillor Sultan Khan resigned from the Labour Party, but continued to represent the ward as an independent before joining the Liberal Democrats.

[6] On 17 July 2019, the Brislington East councillor Tony Carey resigned from the Conservative Party, but continued to represent the ward as an independent before joining the Liberal Democrats[7] A by-election took place in Brislington East on 16 January 2020 after the death of the Labour councillor Mike Langley.

[15] Williams subsequently decided to stand down as the Conservative candidate, choosing instead to run in the regional West of England mayoral election.

The Southmead by-election was triggered following the stepping down of Helen Godwin over time constraint alongside her other job.

[46] The Hotwells and Harbourside by-election was triggered following the stepping down of Alex Hartley over health concerns.

[48] The Bishopston and Ashley Down by-election was triggered following the stepping down of Lily Fitzgibbon due to her moving away from the area.