Joely Kim Richardson was born in Marylebone, London, to the theatrical Redgrave family, the daughter of actor Vanessa Redgrave and director Tony Richardson (1928–1991), and the granddaughter of actors Sir Michael Redgrave (1908–1985) and Rachel Kempson, Lady Redgrave (1910–2003). Actress Natasha Richardson (1963–2009) was her sister and actor Liam Neeson is her brother-in-law. She is the aunt of Micheál Richardson and Daniel Neeson, the niece of Lynn Redgrave (1943–2010) and Corin Redgrave (1939–2010), and cousin of Jemma Redgrave, who is five days younger than Richardson.
Joely appeared as an extra at the age of three in the 1968 version of The Charge of the Light Brigade, directed by her father. Richardson and her sister Natasha's early education began at the independent St Paul's Girls' School in Hammersmith. At age 14, Richardson moved to boarding school at the independent Harry Hopman Tennis School in Tampa, Florida. In 1983, she graduated from the Thacher School in Ojai, California, then returned to London to study at the Royal Academy of Dramatic Art and graduated in 1985.
