Koos (Jakobus Petrus) Prinsloo was born on 15 April 1957 in Eldoret in Kenya and moved to to South Africa with his parents in 1962. He matriculated at Hoërskool Newcastle in 1975 and completed an honors degree in Afrikaans at the University of Pretoria.
His debut collection of short stories, Jonkmanskas, was published in 1982.
From 1982 Koos Prinsloo worked as a journalist in Johannesburg; and later also as sub editor and book editor for the glossy magazine De Kat. He died on 4 March 1994 from Aids-related causes.