The economic history of Rainham is underpinned by a shift from agriculture to industry and manufacture[3] and is now in a period of regeneration, coming within the London Riverside section of the Thames Gateway redevelopment area.

[10] The Murex iron-founders moved to Rainham in 1917 and grew along the river, eventually becoming part of the British Oxygen Company.

Away from the river, other industries included brickmaking and after World War II there was a growth in gravel extraction.

[3] New prosperity from increased trade in the early 18th century led to several new buildings, including Rainham Hall.

[3] The roadways and sewerage systems did not keep up with the rate of growth and a residents' group fought for improvements in infrastructure throughout the 1960s.

[17] The land to the south has been affected by gravel extraction and 200 acres (0.81 km2) of Rainham Marshes has been filled with 9 million tons of dredged soil by the Port of London Authority.

[24] At the 2001 census, there were 4,589 residents who fell into the social category ABC1, which equated to 37.9% of the population in the ward of Rainham and Wennington.

The northern part of Rainham is identified in the London Plan as a local district centre with 20,000 square metres (220,000 sq ft) of commercial floorspace.

[2] Within Havering, it is identified as one of seven town centres in the borough,[25] with a retail area extending along Upminster Road South and Broadway.

[27] In 2006 Havering London Borough Council proposed that land in Rainham could be used for a large regional casino.

[29] Sewage sludge was disposed of by dumping at sea at the Black Deep in the outer Thames Estuary, until this practice was banned in 1998.

[30] In 2012 anaerobic digestion facilities were installed at Riverside, enabling the plant to turn solid waste into enough renewable energy to power the site.

[30] Havering Council's urban strategy recognises that nearby Hornchurch is the main cultural hub of the borough with a large theatre and arts spaces, and Romford offers the largest regional concentration of entertainment facilities.

[35][36] The Belvedere Crossing is a proposed tunnel or bridge, between Belvedere and Rainham[37] On 26 May 2003, Mayor Question Time, then London Assembly member for Havering and Redbridge Roger Evans asked former Mayor of London Ken Livingstone what progress had been made in convincing the government of extending the Docklands Light Railway to Rainham, the mayor responded by saying Rainham would be linked to the DLR at Dagenham Dock by the East London Transit.