An avid drawer, Olsen began his artistic career freelancing as a cartoonist for publications such as Man and Fashion Design, before studying art at the Julian Ashton School in Sydney and East Sydney Technical College. He advanced quickly as an artist and held his first major exhibition in 1955 at Macquarie Galleries, also participating in a key abstract expressionism exhibition,
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Sydney and its iconic sights were of great interest to Olsen after his period abroad and it was here that he established and ran the Bakery Art School, producing some of his best-known works. In 1971, Olsen was commissioned to paint a mural for the Sydney Opera House, and Salute to Five Bells was created. Although inspired by the tragic poem Five Bells by Kenneth Slessor, Salute, a gigantic 70-by-10 foot mural, is a celebration of Sydney Harbour and the life that surrounds the area. In this piece, Olsen showcased his unique, innovative style of painting, often labelled “drawing with paint”, creating a work full of movement, colour and vitality. The work was hung in the northern foyer Opera House where it remains to this day.

In the mid-1970s, Olsen made his first trip to South Australia’s Lake Eyre at flood time and found what he labelled as his “soul place”. The Lake Eyre series demonstrates his deep engagement with the Australian landscape, his experiments with colour blending and soft brushwork showing an extreme reverence for the vastness and mystery of the often bleak land. Most of his pieces are painted from aerial views, capturing the scale and true colour of the scenery and the changeability of the nature within.

Olsen’s works are represented in all Australian national galleries and in public and private collections worldwide. In 2005 he won the Archibald Prize with his painting Self Portrait Janus Faced.

After a sojourn in Europe at the age of 30 that was privately sponsored by a Sydney art critic, Olsen found himself transformed by European influences and the styles and sights of the Mediterranean, and returned to Australia inspired to paint the nature and landscapes of his own country.