The Romford to Upminster Line was constructed in 1893 as a branch of the London, Tilbury and Southend Railway (LT&SR). Property development in the immediate area and in 1908 the proposed new railway station at Gidea Park on the Great Eastern Railway (GER) prompted the LT&SR to construct a station on their branch. The station was opened on 1 October 1909 as Emerson Park Halt on the branch line from Romford to Grays via Upminster, where it connected with the main route from London Fenchurch Street. A run round loop was constructed 500 yards to the west to enable extra trains to run between Emerson Park and Upminster. When push-pull working began in 1934 the loop was not needed and taken out c. 1936. Originally named Emerson Park Halt, and shown in some timetables and on some signage throughout its history as Emerson Park & Great Nelmes, the station name was later simplified to Emerson Park, but the date of this change is not recorded. Even though the station has long been called Emerson Park, one former platform sign installed by National Express East Anglia in the late 2000s read: "Welcome to Emerson Park Halt".
Emerson Park originates from the development of suburban housing in the late 19th century after the coming of the railway. The residential estates that make up the area are named Ardleigh Green, Emerson Park and Nelmes. It is located to the north of Hornchurch town centre and is considered one of the most prestigious neighbourhood in Greater London. Being not far from West Ham United's training ground at Chadwell Heath, the area is popular with West Ham footballers. Former player Rob Lee and current player Diafra Sakho live in Emerson Park. Former player Frank McAvenie and former Arsenal player Ray Parlour "the Romford Pele" have also lived there. The station consists of a side platform located to the north of the single track. Access to the street is provided by a ramp. The station is of basic design and has no buildings other than a platform canopy. There are Oyster card validators and a ticket vending machine. A digital display board underneath the canopy provides departure information. The typical off-peak service is 2 trains per hour in either direction. There is no Sunday Service. All trains leave from platform 1. It is in Travelcard Zone 6. The station has payphones, help points and boarding ramps but no toilets.
Connections: London Buses routes 165, 256 and 370 serve the station, providing connections to Ardleigh Green, Harold Wood, Hornchurch, Lakeside Shopping Centre, Rainham, Romford and Upminster.