Rainham is a suburb of East London, England, in the London Borough of Havering. Historically an ancient parish in the county of Essex, Rainham is 13.6 miles (21.9 km) east of Charing Cross and is surrounded by a residential area, which has grown from the historic village, to the north and a commercial area, fronting the River Thames, to the south. As part of the suburban growth of London in the 20th century, Rainham significantly expanded and increased in population, becoming part of Hornchurch Urban District in 1934, and has formed part of Greater London since 1965. The economic history of Rainham is underpinned by a shift from agriculture to industry and manufacture and is now in a period of regeneration, coming within the London Riverside section of the Thames Gateway redevelopment area.

The London Borough of Havering in East London, England, forms part of Outer London. It has a population of 259,552 inhabitants; the principal town is Romford, while other communities are Hornchurch, Upminster, Collier Row and Rainham. The borough is mainly suburban, with large areas of protected open space. Romford is a major retail and night time entertainment centre, and to the south the borough extends into the London Riverside redevelopment area of the Thames Gateway. The name Havering is a reference to the Royal Liberty of Havering which occupied the area for several centuries. The local authority is Havering London Borough Council. It is the easternmost London borough.