The Mayor of London is an elected politician in London, England, who heads the Greater London Authority and is responsible for budgeting and strategic planning of some governmental functions across the whole of Greater London. These include transport, the police, fire and emergency services and economic development. The first elected Mayor of London is Ken Livingstone.

The Mayor is elected for a fixed term of four years, with the first election being held in May 2000. The 2000 campaign was incident filled. The eventual winner, Ken Livingstone, went back on a pledge not to run as an independent after losing the Labour nomination to Frank Dobson. The Conservatives had to replace Jeffrey Archer as their candidate when he was charged with perjury; Steven Norris was selected as his replacement despite tabloid revelations about his many extra-marital affairs.

There is also a Lord Mayor of London for the City of London, an ancient and now mostly ceremonial post.