In his early 20s, he found himself in Paris on the promise of an acting job. He was installed in an apartment by an older man and paid a generous stipend. Meals and gifts came his way from assorted male admirers; one composed love poems in his honor.
During the nineties, Björn lived with Teresa Schmiterlöw, with whom he produced several music and theatre works.
As an adult he often worked as a music teacher between acting roles.
Like Mark Lester and Jack Wild, and later Leif Garrett, Andrésen was especially popular in Japan during the 1970s. He appeared in several television advertisements there, and recorded several pop songs.
Resides in Stockholm. He has a daughter, Robine. Björn and his ex-wife Susana Roman had another child, a boy, Elvin (their first child), who died of
Sudden Infant Death Syndrome in 1986.