He was a freelance illustrator providing illustration to many children's book authors such as van Guus Kuijer, Els Pelgrom, Sylvia Vanden Heede and Dolf Verroen. Tjong-Khing won the "Gouden Penseel" (Golden Brush) award three times, and in 2005 won the "Woutertje Pieterse Prijs" for his book "Waar is de taart?" (Where is the cake?). 