Teitelbaum studied from 1950 to 1951 at the California School of Fine Arts with Clyfford Still and at Mills College with Max Beckmann.
[2] At first, Teitelbaum painted his own form of portraits featuring expressionism, then landscapes of various regions in Canada.
[2][3] His style became increasingly abstract throughout his years of painting, going through many changes, among them single Zen-like improvised gestures on unprimed canvas.
[4] In his final years, Teitelbaum repeatedly picketed the Art Gallery of Ontario for its failure to support contemporary Canadian artists.
[4] Mashel Teitelbaum was described as a "brilliant but mercurial" artist, afflicted by bipolar disorder by the Toronto Star in 2009.