Born in Los Angeles, Michael Gallagher attended UCLA and Yale Universities and studied painting and drawing with David Hockney, Alfred Leslie, Jan Stussy, Sam Amato & Richard Diebenkorn, Edgar Ewing and Keith Crown at USC. He later studied with George Wardlaw, Robert Motherwell, Helen Frankenthaler, Robert Mangold, Walker Evans, Knox Martin, Jack Tworkov, Lester Johnson, Bill Bailey, Bernard Chaet, Dick Lytle, Josef Albers, Al Held, Gabor Peterdi and Barbara Rose.

He had his first of many one man shows in Soho, New York at Razor Gallery in 1974. In 1978 his work was included in several museum shows. His first & second show at the Louis Meisel Gallery sold out before the opening, and his painting, Pralaya, 1979, was purchased by the Guggenheim Museum.

He participated in the group show, "The Reality of Illusion", which traveled to numerous museums across the United States. His series of large monotype collages, were published by Fred Dorfman at Andy Warhol's studio in 1987