Piccadilly Circus connects to Piccadilly, a thoroughfare whose name first appeared in 1626 as Piccadilly Hall, named after a house belonging to one Robert Baker, a tailor famous for selling piccadills, or piccadillies, a term used for various kinds of collars. The street was known as Portugal Street in 1692 in honour of Catherine of Braganza, the queen consort of King Charles II of England but was known as Piccadilly by 1743. Piccadilly Circus was created in 1819, at the junction with Regent Street, which was then being built under the planning of John Nash on the site of a house and garden belonging to a Lady Hutton. The circus lost its circular form in 1886 with the construction of Shaftesbury Avenue.
The junction has been a very busy traffic interchange since construction, as it lies at the centre of Theatreland and handles exit traffic from Piccadilly, which Charles Dickens, Jr. described in 1879: "Piccadilly, the great thoroughfare leading from the Haymarket and Regent-street westward to Hyde Park-corner, is the nearest approach to the Parisian boulevard of which London can boast."
The Piccadilly Circus tube station was opened 10 March 1906, on the Bakerloo Line, and on the Piccadilly Line in December of that year. In 1928, the station was extensively rebuilt to handle an increase in traffic.
The intersection's first electric advertisements appeared in 1910, and, from 1923, electric billboards were set up on the facade of the London Pavilion. Traffic lights were first installed on 3 August 1926, at the junction.