The Science Museum Group (SMG) is the corporate name for the The Board of Trustees of the Science Museum, the latter body was established under the National Heritage Act 1983, when the Science Museum and its sister museums were devolved from direct Civil Service control. The name National Museum of Science and Industry (NMSI), which had been in use as the Science Museum's subtitle since the early 1920s, was adopted as the corporate name of the entire institution in 1984, before this the National Railway Museum and the National Museum of Photography, Film & Television (now named the National Science and Media Museum) were known as outstations of the Science Museum. In 2012 the name of the organisation was changed from NMSI to the Science Museum Group.

The SMG has the status of a non-departmental public body (NDPB), operating within the public sector but at arm’s length from its sponsor department, the Department for Culture, Media and Sport (DCMS). The SMG is a charity, with DCMS acting as its principal regulator for charity law purposes. It also has a wholly owned subsidiary trading company, SCMG Enterprises Ltd., formerly NMSI Enterprises Ltd. and NMSI Trading Ltd., was set up in 1988 operating across all SMG museums.

The Science Museum traces its origins back to the Great Exhibition of 1851, and the South Kensington Museum (SKM) which opened on the site of what is now the Victoria and Albert Museum in 1857. The site also hosted The Patent Office Museum, whose collections were formally transferred to SKM in 1883. In 1863 the science collections were moved to separate buildings on Exhibition Road. In 1909 the Science and Engineering Collections were separated administratively and the name ‘Science Museum’ was officially adopted, the SKM’s art collections were re-named to ‘The Victoria and Albert Museum’.

The National Railway Museum (NRM) was established in 1975 as a result of the transfer of the British Transport Commission’s railway collection, previously held at the Museum of British Transport, Clapham, to the Board of Trustees of the Science Museum.

The National Science and Media Museum, formerly the National Media Museum and the National Museum of Photography, Film & Television, was established by the Science Museum in 1983 with the support of Bradford City Council.

Locomotion at Shildon in County Durham was officially opened in September 2004. It was a partnership between the National Railway Museum and local authority partners, jointly funded by all the parties, the Heritage Lottery Fund and other funders. It incorporates historic buildings that were part of Sedgefield Borough Council’s Timothy Hackworth Museum.

The Science and Industry Museum, formerly known as the Museum of Science and Industry, the Museum of Science and Industry in Manchester, the Greater Manchester Museum of Science & Industry and the North Western Museum of Science and Industry, was transferred to the Board of Trustees of the Science Museum in 2012.

A large former airfield at Wroughton, near Swindon, was acquired in 1979 both for storage of existing collections and to allow the development of collections of larger full-size objects such as aeroplanes and commercial road vehicles. In 2018 it was re-named to the National Collections Centre (NCC) at the beginning of a project to provide storage for and to facilitate public access to objects decanted from Blythe House, a former government museum storage building in West London.