Arriva London is a major bus company operating services in Greater London. It is a subsidiary of Arriva UK Bus and operates services under contract to Transport for London. It was formed in 1998 from a fusion of previously separate Arriva subsidiaries Grey-Green, Leaside Buses, Kentish Bus, London & Country and South London Transport. Operations are split between two registered companies, Arriva London North Limited and Arriva London South Limited.

Arriva UK Bus is a major bus operator in the United Kingdom based in Sunderland, England. It is a subsidiary of Arriva which runs transport services across Europe, which was a subsidiary of Deutsche Bahn from 2010. As of 2024 Arriva will be owned by I Squared Capital.