The role was created in 2000 after the Greater London devolution referendum in 1998, and was the first directly elected mayor in the United Kingdom.

The position was held by Ken Livingstone from the creation of the role on 4 May 2000 until he was defeated in May 2008 by Boris Johnson, who then also served two terms before being succeeded by Khan.

As with most elected posts in the United Kingdom, there is a deposit (in this case of £10,000), which is returnable on the candidate's winning of at least 5% of votes cast.

In August 2003, Livingstone oversaw the introduction of the Oyster card electronic ticketing system for Transport for London services.

Livingstone, in a mayoral election debate on the BBC's Question Time in April 2008, stated that the primary reason he supported the Olympic bid was to secure funding for the redevelopment of the East End of London.

In May 2008, Boris Johnson introduced a new transport safety initiative to put 440 high visibility police officers in and around bus stations.

[13] A ban on alcohol on underground, and Docklands Light Railway, tram services and stations across the capital was introduced.

[15] In 2010, he extended the coverage of Oyster card electronic ticketing to all National Rail overground train services.

In 2011, Boris Johnson set up the Outer London Fund of £50 million designed to help facilitate improve local high streets.

[22] In March 2013, Johnson announced £1 billion of investment in infrastructure to make cycling safer in London, including a 15-mile (24 km) East to West segregated 'Crossrail for bikes'.

[26] Upon election, Khan outlined a vision to make London the "greenest city" by investing in walking and cycling infrastructure while reducing polluting vehicles.

[27] In 2019, the "Ultra Low Emission Zone" scheme was launched which taxes highly polluting vehicles in its covered territory.