Thamesmead lies 9 miles east of Charing Cross, and includes a group of disparate developments, mainly social housing, built from the late 1960s onwards, mostly on former marshland on the south bank of the River Thames, between the established towns of Woolwich and Belvedere. Originally planned to have 60,000-100,000 residents, it is now estimated to be on target for a final population of around 50,000.

Most of the land area of Thamesmead previously formed about 1,000 acres of the old Royal Arsenal site that extended over Plumstead Marshes and Erith Marshes.

Much of Thamesmead was initially built by the Greater London Council (GLC) for rent to families moving from overcrowded back-to-back Victorian housing in south eastern parts of Inner London. The area had been inundated in the North Sea Flood of 1953, so the original design placed living accommodation at first floor level or above, used overhead walkways and left the ground level of buildings as garage space.[6] The first residence was occupied in 1968, but already there were rain penetration problems. The pre-1974 parts of Thamesmead are a mix of modernist town houses, medium-rise and 12-storey blocks system-built in concrete, which have featured in various films due to their 'rough urban look'; the design of the newer buildings is more traditional and in brick.

When the GLC was abolished in 1986, its housing assets and the remaining undeveloped land were vested in a non-profit organisation, Thamesmead Town Limited (TTL). TTL was a private company with an unusual form of governance. Its nine executive directors were local residents; they periodically submitted themselves to re-election.

In 2000, TTL was wound down and two new organisations were formed. In broad terms, Gallions Housing Association took over the ownership and management of the housing assets whilst Tilfen, later Tilfen Land, took over the remaining undeveloped land.

Before the 20th century developments, there is some evidence of prehistoric human occupation of the area: flints, animal bones and charcoal were found in bore holes around Western and Central Way in 1997 by the Museum of London Archaeological Service (MOLAS). In Roman times, the river level was significantly lower, and work by MOLAS in 1997 around Summerton Way revealed evidence of field ditches and pottery and quernstones from Germany dating from around the 3rd or 4th century. After the Roman era, river levels rose again and the area reverted to marshland. According to Hasted, some areas of this marshland were drained by 1279 by the monks of Lesnes Abbey. Between 1812 and 1816, a canal was built by convicts to take materials such as timber from the River Thames to Woolwich Royal Arsenal. Much of this canal has been filled in, but part remains in Thamesmead West and is now called the Broadwater. A disused lock gate and swing bridge over the canal still exist beside the River Thames.