The son of a rabbi, Leslie Rubin was born on 5 August 1909 in District Six, Cape Town, Cape Province (now Western Cape), then a multiracial district of the city. He was educated at Durban High School in Natal (now KwaZulu-Natal), before attending the University of Cape Town (UCT), the University of the Witwatersrand, Transvaal Province (now Gauteng), and the University of South Africa (UNISA) respectively.