Polling stations opened their doors at 07:00 BST and will close at 22:00.
Votes are being cast to elect the mayor of Bristol, Bristol City Council councillors, and the police and crime commissioner (PCC) is being elected for Avon and Somerset.
Elsewhere in England, elections are taking place for more than 120 councils, and to elect mayors in Liverpool, London and Salford.
Voting has begun in elections being held in Bristol.