Nils Andersen was born in Drammen, Norway. He studied Art at Natal Tech Art School in Durban, under OJP Oxley and Alfred R Martin in 1928 and ceramics at Natal Tech Art School in 1938.
His childhood was spent at sea with his father, a Norwegian Master Mariner. They moved to South Africa and lived in Durban from 1912, but Anderson traveled widely across Southern Africa; camped out on several trips to Namibia with Mr. E Schweikerdt of Pretoria. He drew and painted from an early age until he began formal art studies. In 1933 Nils Andersen commenced a fulltime career as an artist, making art works in various paint and graphic media, initially favoring watercolor. He is famed for his seascapes.
Between 1942 and 1944 he taught art and ceramics at Durban Tech. In 1962 Nils Andersen took ill and painted very little thereafter. Several of his works have been reproduced locally by E Schweikerdt (Pty) Ltd; and one from the collection of King Haakon VII of Norway was reproduced in that country.