The station was opened on 1 May 1903 as part of the Great Eastern Railway's (GER) Fairlop Loop branch line from Woodford to Ilford. The line was designed to stimulate suburban growth but was closed on 1 October 1908 due to a lack of custom and did not reopen until 2 March 1930. In 1923, GER was merged with other railway companies to form the London & North Eastern Railway (LNER) under the 1921 Railways Act. Alterations at Hainault included a new island platform on the west side of the station to allow the bulk of services via Gants Hill to be terminated here as well as allowing access to Hainault Depot. This, situated to the north of the station, is the major train depot on the eastern end of the line. The depot building was completed in 1939 but was used by the US Army Transportation Corps until 1945. The name Hainault was recorded as 'Henehout' in 1221 and 'Hyneholt' in 1239. It is Old English and means 'wood belonging to a religious community', referring to the ownership of Hainault Forest, part of the larger Epping Forest, by Barking Abbey. The spelling was altered from the 17th century because of a false connection to Philippa of Hainault, the wife of Edward III.
The station has recently been the focus of a refurbishment programme. The ticket office has been refurbished, a new Station Supervisor's Office in the ticket hall was completed in June 2009 and lifts have been installed to allow step-free access to the platforms. Hainault is half a mile (800 m) from Fairlop Station, which can be seen from the platforms by looking down the line The lifts are the shallowest on the London Underground network, having a descent of just 0.67 metres. The station has toilets, payphones, a bridge, waiting room, lifts, boarding ramps and a car park.
Connections: London Bus routes 150; 167; 169; 247; 275 and 462, and night route N8 serve the station.