Events from the year 1873 in the United Kingdom.
- 3 March – first performance of W. S. Gilbert and Gilbert Arthur à Beckett's play The Happy Land at the Royal Court Theatre, London. The play creates a scandal by breaking regulations against the portrayal of public characters, parodying William Ewart Gladstone, Robert Lowe, and Acton Smee Ayrton, respectively the Prime Minister, Chancellor of the Exchequer, and First Commissioner of Works.
- 13 March – Gladstone resigns as Prime Minister, but the Conservatives fail to form a government, and Gladstone returns to office two days later.
- 31 March – Supreme Court of Judicature Act reforms the judiciary, establishing the Supreme Court and Court of Appeal of England and Wales and abolishing the Court of Common Pleas as a separate institution and, with it, the office of attorney at law.
- April – Ashanti attack British forts in the Gold Coast.
- 1 April – the British steamer RMS Atlantic sinks off Nova Scotia killing 547.
- 2 April – the first sleeping car is introduced in Britain, on the Glasgow to London night express.
- 4 April – the Kennel Club, the world's first kennel club, is founded in London by Sewallis Shirley (MP).
- 20 May – in Chipping Norton, rioters attempt to free the Ascott Martyrs – sixteen women sentenced to imprisonment for attempting to dissuade strikebreakers in an agricultural labour dispute.
- 9 June – Alexandra Palace in London destroyed by fire only a fortnight after its opening.
- 18 June – Alice Vickery passes the Royal Pharmaceutical Society's examination, becoming the first qualified female pharmacist in the U.K.
- October – Girton College opens as the first women's college in Cambridge.
- 26 November – British troops invade Ashanti territory.
- 7 February – Thomas Andrews, shipbuilder (died 1912)
- 19 April – Sydney Barnes, cricketer (died 1967)
- 25 April – Walter de la Mare, poet, short story writer and novelist (died 1956)
- 26 April – Roy Redgrave, silent film actor (died 1922)
- 8 May – Nevil Sidgwick, chemist (died 1952)
- 17 May – Dorothy Richardson, feminist writer (died 1957)
- 11 August – Bertram Mills, circus manager (died 1938)
- 22 November – Johnny Tyldesley, cricketer (died 1930)
- 17 December – Ford Madox Ford, writer (died 1939)
- 22 December – Lily Montagu, pioneer of reform Judaism (died 1963)
- 26 December – Thomas Wass, Nottinghamshire bowler (died 1953)
- 9 January – Napoleon III, deposed Emperor of the French (born 1808 in France)
- 18 January – Edward Bulwer-Lytton, novelist (born 1803)
- 7 February – Sheridan Le Fanu, writer (born 1814)
- 24 March – Mary Ann Cotton, serial murderer (born 1832; hanged)
- 27 April – William Charles Macready, actor (born 1793)
- 1 May – David Livingstone, explorer of Africa (born 1813)
- 8 May – John Stuart Mill, philosopher (born 1806)
- 18 July – Sir David Salomons, banker and campaigner for emancipation of the Jews in England (born 1797)
- 20 July – Richard Bethell, 1st Baron Westbury, Lord Chancellor of Great Britain (born 1800)
- 17 September – Alexander Berry, adventurer and Australian pioneer (born 1781)
- 1 October – Sir Edwin Landseer, painter (born 1802)