A by-election was held in the UK Parliament constituency of Old Bexley and Sidcup on 2 December 2021, following the death of the sitting member of parliament, James Brokenshire, who had been the Conservative MP for the constituency since 2010. The by-election was the fifth of the 58th Parliament, which was elected in 2019. The election was won by Conservative candidate Louie French with a reduced majority.