The square, nearby Fitzroy Street, and the Fitzroy Tavern in Charlotte Street have the family name of Charles FitzRoy, 2nd Duke of Grafton, into whose ownership the land passed through his marriage. His descendant Charles FitzRoy, 1st Baron Southampton developed the area during the late 18th and early 19th century.
Fitzroy Square was a speculative development intended to provide London residences for aristocratic families, and was built in four stages. Leases for the eastern and southern sides, designed by Robert Adam, were granted in 1792; building began in 1794 and was completed in 1798 by Adam's brothers James and William. These buildings are fronted in Portland stone brought by sea from Dorset.
The Napoleonic Wars and a slump in the London property market brought a temporary stop to construction of the square after the south and east sides were completed. According to the records of the Squares Frontagers' Committee, 1815 residents looked out on 'vacant ground, the resort of the idle and profligate'. Another contemporary account describes the incomplete square:
'The houses are faced with stone, and have a greater proportion of architectural excellence and embellishment than most others in the metropolis. They were designed by the Adams, but the progress of the late war prevented the completion of the design. It is much to be regretted, that it remains in its present unfinished state'.
Today, the square is largely pedestrianised (scheme designed by Sir Geoffrey Jellicoe). In 2008 the square was upgraded by relaying most of the surface at a single level, removing street clutter such as bollards, and further restricting vehicular access. 
The Square is at the heart of the Fitzrovia conservation area, and the subject of the Fitzroy Square conservation area appraisal and management strategy adopted by the London Borough of Camden in March 2010.
The square has a number of notable buildings, many with distinguished connections marked by blue plaques.
Numbers 1, 1A, 2-8 and 33-40 are grade I listed buildings.
- No. 6 holds the office and library of the Georgian Group.
- No. 7 was the home of Sir Charles Eastlake, first director of the National Gallery.
- No. 8 was the home of the painter James McNeill Whistler.
- No. 9 was the home of chemist August Wilhelm von Hofmann (1818–1892).
- No. 13-14 was home to St Luke's Hospital for the Clergy (1904-2009).
- No. 19 was the base for the 'International School' run by Louise Michel in the 1890s. Later it was the home of Bloomsbury Group artist Duncan Grant (c. 1909).
- No. 21 was the home of English statesman and Prime Minister Lord Salisbury. It is now occupied by the High Commission of Mozambique.
- No. 23 is the Embassy of Liberia.
- No. 27 was the home of theatre critic and occasional Shaw collaborator William Archer.
- No. 28 is the headquarters of the Magistrates' Association.
- No. 29 was the home of George Bernard Shaw from 1887 until his marriage in 1898; and later of Virginia Woolf 1907-1911.
- No. 33 housed Roger Fry's Omega Workshop, creating avant-garde furniture from 1913 to 1919.
- No. 34-35, owned by Guy Ritchie, was controversially squatted as the London Free School in 2011.
- No. 37 was the home of the artist Sir William Quiller Orchardson from 1862, an address he shared for three years with John Pettie. Later it was the home of the artist Ford Madox Brown and childhood home of his grandson, the writer Ford Madox Ford.
In addition to those above:
- Epidemiologist William Farr (1807–1883) established his first medical practice in Fitzroy Square.
- William Nisbet (1759–1822) - Scottish physician and medical writer practised in Fitzroy Square after 1801.
Culture and media
It was a filming location for the BBC's 2009 adaptation of Jane Austen's "Emma".
- Tottenham Court Road in Old and New London: Volume 4 (1878), pp. 467-480, from British History Online
- 10 Fitzroy Square
- Leigh's New Picture of London. Printed for Samuel Leigh, 18, Strand; by W. Clowes, Northumberland Court. 1819
- Fitzroy Square Garden
- Books and Writers - Bloomsbury Group
- Mrs Aria, My Sentimental Self, Chapman & Hall 1922, pp241-242
- A 360 degree view from Urban75