'Upton' is thought likely to mean at the high-lying farmstead.
The hamlet of Upton, on Upton Lane in West Ham, is first recorded as Hupington in 1203. 'Park' was added for marketing to a housing estate dated by Wikipedia and Londonist to the 1880s – yet the station, built by the estate's developer and named after it, opened in 1877. West Ham United's former stadium, the Boleyn Ground, was commonly known as Upton Park.