Ntuli was born in the uBombo district, northern Zululand. He received his primary school education at the Ndaleni Practising School, Richmond, at the Ndaleni Secondary School and from 1972 - 1975 at the Dlangezwa High School where he took his matric.
From 1969 - 1973 he attended the Ndaleni Teachers Training College in Richmond, specialising in art. He taught at schools in KZN between 1976 and 1977.
From 1978 to 1983 he studied for a BA(FA) at the University of Fort Hare. Ntuli undertook further studies at the Royal College of Art, London, from 1984 to 1986. From 1978 to 1988 he lectured in art at the University of Bophuthatswana and at the Hebron College of Education. Between 1992 and 2000 he lectured in Painting at the University of Durban-Westville.
Ntuli has served as a juror on national art exhibitions and has served as a member of the Board of Trustees of various SA art institutions including the African Art Centre, BAT Centre, Durban Art Gallery and the Funda Art Centre. His work is represented in public and private art collections in SA and abroad.