She was born in London, England as Dorothy Katherine Standing, the daughter of Sir Guy Standing and his wife, Dorothy. Her grandfather was Herbert Standing (1846–1923) and her uncles were Wyndham, Percy and Jack Standing, as well as Herbert Standing Jr., father of Joan Standing.
She studied at RADA and first appeared on the London stage in 1927. Her most famous role was that of Elvira in Noël Coward's Blithe Spirit, which she played in the original stage production. She reprised her role in the 1945 film version opposite Rex Harrison, Margaret Rutherford and Constance Cummings.
Kay Hammond died in Brighton, aged 71, from undisclosed causes, on 4 May 1980.
