Andersen was born in Copenhagen.[1] In his childhood, he enjoyed Scandinavian comics, such as works by the Danish cartoonist Storm P., and Franco-Belgian comics.[1][2] As a student, it was clear for Andersen to become a professional artist. After finishing school and military service, he searched for a job as an illustrator, preferably at advertising agencies and newspapers. Andersen learned that the media group Egmont, the Danish publisher for Disney comics, searched for artists.[2][3] After he sent his illustrations, he was hired by Egmont in 1991, but not as an advertising illustrator. At first, Andersen wrote the stories for Disney comics, but in 1992, he started drawing the comics himself.[3][4]