Hewitt has performed around the world in recital and as soloist with orchestra. She is best known for her cycle of Bach recordings which she began in 1994 and finished in 2005—covering all of the major keyboard works of J. S. Bach. Her recording of Bach's "The Art of Fugue" was released on October 17, 2014. Her discography also includes works by Louis Couperin, Jean-Philippe Rameau, Olivier Messiaen, Emmanuel Chabrier, Maurice Ravel, Robert Schumann, Ludwig van Beethoven, Frédéric Chopin, Claude Debussy and Gabriel Fauré. She has recorded two discs of Mozart concertos with the Orchestra da Camera di Mantova, and a third with Ottawa's National Arts Centre Orchestra, conducted by Hannu Lintu. With the DSO Berlin and Lintu, she also recorded the Schumann Piano Concerto.