Al Hansen, a native of New York, began art training in 1949 by studying. From 1960 he studied under John Cage, who would later become a good friend, at the New School for Social Research in New York.
At the same time Al Hansen came into contact with the Fluxus movement and began developing mixed-media Environments.
Hansen was a pioneering exponent of "Performance" and "Happenings". Not long after being stationed with the US forces in Frankfurt, Al Hansen dropped a piano from the roof of a bombed-out house. Back in New York, Hansen repeated this Action several times; it was later called the "Yoko Ono Piano Drop".
As an early member of Fluxus, Al Hansen took part in numerous international Fluxus festivals with his Performances. A friend of Andy Warhol's, Hansen was a frequent guest at "the Factory". In 1965 Al Hansen summed up his work in book form as A Primer of Happenings and Time Space Art. Hansen also did collages, in which his main theme was Venus.
In the early 1980s Al Hansen moved to Cologne, where he and Lisa Cieslik founded "the Ultimate Academy" in 1987, which is still an important forum for young artists from all over the world.
Al Hansen continued to live and work in Cologne until his death in 1995.