Raised in Cape Town's District Six, Gavin Jantjes attended the Michaelis School of Fine Art, University of Cape Town from 1967 to 1970. He began to exhibit locally in 1968, using his art to speak out against racism.
In the 1970s he went into exile in Germany where he completed his MA in Fine Art at Hochschule für Bildende Künste in 1972 and produced his "South African Colouring Book (1974/1975), a radical stocktaking of South African reality. He also worked on successful anti-apartheid poster campaigns for the UNHCR. This led to the banning of all his work by the apartheid regime.
From 1986 to 1990 he was the first black council member of the Arts Council of Great Britain. During this time he was responsible for the development of the Arts Council's policy on cultural diversity set out in the report "Toward Cultural Diversity". In 1992 he was the Arts Council's consultant for the creation of the Institute of International Visual Art (inIVA), and co-ordinated the "New Internationalism" symposium for inIVA with the Tate Gallery in May 1994.
He served as a trustee of the Whitechapel Gallery from 1986 to 1994, as an adviser to the Tate Gallery in Liverpool from 1992 to 1995 and as a Trustee of the Serpentine Gallery in London from 1995 to 1998.
In the period 1986-1998 he held a senior lectureship at Chelsea College of Art, The London Institute.
In 1998 he was appointed as Artistic Director of the Henie-Onstad Kunstsenter in Oslo, Norway. He initiated the "Oslo Open" for the city of Oslo in year 2000, and has been an advisor to the Norwegian Arts Council since 1999. He is also a member of the appointments committee for Documenta 12.
His essays and lectures have been published in many international publications and art journals. His curatorial research on internationalism has shaped the program at Henie-Onstad Art Centre and is outlined in "A Fruitful Incoherence: dialogues with artists on internationalism" published by inIVA London.