Upon completing studies at the National Academy of Design in 1895, Oscar Fehrer honed his artistic skill at the Royal Academy in Munich and the Academie Julian in Paris, and returned to Manhattan by 1900. In the next few decades he lived and worked in New York, Munich, the Berkshires, and Provincetown, Massachusetts. He spent his summers in Pleasant Valley, Connecticut after 1918, in close proximity to the thriving art colony centered at Old Lyme. He lived primarily in Connecticut after 1930 while maintaining a studio space in New York.

Fehrer was a member of the Salmagundi Club, the Allied Artists of America in New York City, the Brooklyn Painters and Sculptors, the Brooklyn Society of Artists, the Connecticut Academy of Fine Arts, the Springfield Artists' League, and, in 1915, he was elected a life member of the National Arts Club in New York City.