First Bus London
| Parent | FirstGroup | 
|---|---|
| Founded | February 28, 2025 | 
| Headquarters | London | 
| Service area | Greater London | 
| Service type | Bus operator | 
| Depots | 10 | 
| Fleet | 982 (February 2025) | 
| Fuel type | Diesel and electric | 
| Managing directors | Colin Brown Bill Cahill | 
| Website | www.firstbus.co.uk | 
First Bus London is a bus operator running services across Greater London, England. It is a subsidiary of FirstGroup, operating buses under contract to Transport for London, and was formed with the purchase of RATP Dev Transit London from RATP Group in 2025.