Capital Citybus was established on 29 December 1990, with the purchase of the London tendered bus services of Ensignbus by the Hong Kong businessman Tsui Tsin-tong's CNT Group, which also owned bus operator Citybus.

Capital Citybus also operated six commercial routes, mainly in the Romford area, and Hertfordshire County Council-contracted service 321 (Rickmansworth - Luton) on Sundays.

The company settled on an allover yellow livery with stylised C logos either side of the destination blind on the front of the bus.

After the sale of the company to its management, the fleetname was subsequently modified to just Capital Citybus.

[6] Capital Citybus was a frequent contractor for British Rail and London Underground replacement service work, and during its existence operated specially liveried vehicles for Docklands Light Railway and the East London Line replacement services.