Ingibjörg Sólrún Gísladóttir was born in Reykjavík on 31 December 1954, the daughter of salesman Gísli Gíslason (born 30 November 1916, died 23 October 2006) and homemaker Ingibjörg J. Níelsdóttir (born 23 February 1918).
She received her bachelor's degree in history and literature from the University of Iceland in 1979.