Although he spent some years working for Time magazine, McKnight has devoted his time exclusively to painting since 1972 and, since 1973, has been given over one hundred one-man shows throughout the United States, as well as in Europe and Japan.
His artwork is included in the permanent collection of the Metropolitan Museum of Art, as well as numerous and prominent private, public, corporate and university collections. In addition, four books have been published devoted to his works.
McKnight and his wife, Renate, who is actively involved in his career, continue to travel extensively to gain inspiration for his painting and currently work in their homes in New York and Palm Beach, Florida.