In administrative terms, it lies within the City of Westminster's West End Ward as well as the Harley Street Conservation Area.

In the late 19th/early 20th century, following the expiration of individual buildings’ 99-year leases, Hallam Street was redeveloped and many of its original Georgian houses were replaced by larger mansion and office blocks.

[6] Notable residents who lived for a time in the street include the Pre-Raphaelite artist and poet Dante Gabriel Rossetti (1828–1882), the painters John Sell Cotman (1782-1842), Cornelius Varley (1781-1873),[7] Sir Peter Francis Bourgeois(1753–1811), dominatrix Theresa Berkley (d.1836), the writer William Gerhardi (1895–1977), the conductor and founder of The Proms Sir Henry Joseph Wood (1869–1944),[8] American journalist and broadcaster Edward R Murrow (1908–1965), World War Two hero Wing Commander Forest Frederick Edward Yeo-Thomas (1901–1964), the radio and television writer Ernest Dudley (1908–2006), and the Austrian writer Stefan Zweig (1881–1942).

Numbers 44 and 50 Hallam Street, originally the offices of the General Medical Council, received Grade II designation in 1954.

Its redevelopment is the BBC's single largest capital project ever, and has created a new centre for radio, news and world service in the heart of London.