Cahén's career is traceable back to his first one-man show in Copenhagen in the 1930's (before he was twenty), and in Canada, particularly when his work was juried into the Annual Spring Show of the Ontario Society of Artists in 1947. 

 

Post '47, Cahén exhibited with a number of Societies including the Royal Canadian Academy, the Canadian Society of Painters in Watercolour and the Canadian Society of Graphic Art, among others. 

 

Oscar was also exhibiting with local artists. The income he earned from his illustrations subsidized his abstract work. One of the shows Oscar participated in was ‘Abstracts at Home’ in 1953. This show hung at Simpsons' in Toronto, and proved to be a rubicon for contemporary art in Canada. 

 

Artists in this show, including William Ronald, Jack Bush and Jock Macdonald, would go on to form the Painters Eleven. The Group's purpose was to provide a context for their work through cöoperative exhibitions. Painters Eleven met to discuss opportunities, contemporary developments and to see and critique each others’ work.

  

Some of Cahén's earliest works are reminiscent of German religious and figurative expressionism, with dark and moody subjects. By the early 1950's Cahén's paintings developed a more formal structure with broader and stronger colours reflecting the artist's interest in contemporary painting, and followed experimentation with cubism that would begin Cahén's exploration of abstract forms. By 1954 Cahén's work often featured monochromatic areas of fluid, organic forms that had lost all traces of cubism.

 

Cahén's importance as an artist cannot be overstated. His studies of colour influenced the exploration of abstraction and a generation of artists in Canada. The value of Cahén's work came from his freedom and integrity of immediate personal expression. As the editor of Canadian Art, Donald W. Buchanan explained, "Cahén does not paint things as they are but as he is. He depicts not what he sees but feelings the subject provokes in him”.