On 1 December 2016, a by-election was held in the UK parliamentary constituency of Richmond Park. It was triggered by the resignation of the Conservative Member of Parliament Zac Goldsmith on 25 October 2016 over the Government's proposal for a third runway at the nearby Heathrow Airport. It was won by Sarah Olney of the Liberal Democrats, after a campaign focused on opposition to Brexit.

The 2016 London mayoral election was held on 5 May 2016 to elect the Mayor of London, on the same day as the London Assembly election. It was the fifth election to the position of mayor, which was created in 2000 following a referendum in Greater London. The election used a supplementary vote system.