In 1975, Hewitt won the Chopin Young Pianists' Competition in Buffalo, New York, and a Bach competition in Washington, D.C. In 1979, she won third prize in the Robert Casadesus International Piano Competition, since renamed the Cleveland International Piano Competition. In 1978, she won piano division in the CBC Radio Competition and in 1980 the Dino Ciani Competition in Milan, Italy. In 1985, she won first prize in the Toronto International Bach Piano Competition, which led to a recording with Deutsche Grammophon. In 1986, she was named artist of the year by the Canadian Music Council.