David Cox grew up on sheep and cattle stations in Western Queensland, beginning school through correspondence. Later he attended primary schools in Charleville and Toowoomba then Rockhampton Grammar School.
Cox worked on rural stations for five years in the Blackall and Quilpie districts of Queensland. In 1954 he enrolled at the St Martin's School of Art in London. In his first year of study, he received his first commission to illustrate a book, a task that he completed under the direction of Sheila Hawkins. Cox spent eight years in Europe, mainly in London, but also painting in France and Spain.
In 1962 he returned to Australia and worked for the Courier-Mail in Brisbane. He has received commendations and awards for his children's books in addition to a Walkeley Award for newspaper illustration in 1978. Cox has also co-authored a book on Indonesian travel, children's drama and written lyrics for numerous music scores composed by his wife, Betty Beath (q.v.). He has lived for many years in the Brisbane suburb of Highgate Hill.