The inaugural Cambridgeshire and Peterborough mayoral election was held on 4 May 2017 to elect the Mayor of Cambridgeshire and Peterborough. The supplementary vote system was used to elect the mayor for a four-year term of office. Subsequent elections will be held in May 2021 and every four years after. The mayoral election was on the same day as the Cambridgeshire County Council election being held across most of the county except Peterborough, which is administered separately as a unitary authority outside the area covered by the county council.