Michael Penn is a critically acclaimed singer/songwriter and film Composer. Prior to the release of his 1989 debut album March, Penn was a member of the Los Angeles band Doll Congress, and had appeared as an extra on a few television series, including St. Elsewhere.

March, particularly the first single, "No Myth," brought Penn attention, as well as the 1990 MTV Video Music Award for Best New Artist. Penn's follow-up albums Free-for-All (1992), Resigned (1997), MP4: Days Since a Lost Time Accident (2000), Mr. Hollywood Jr., 1947 (2005) and Palms and Runes, Tarot and Tea (2007) weren't able to match the commercial success of March, although critics continued to praise his songcraft.

He has worked extensively creating original music for film; among his first work in this field (if not the first) was for 1993's Tales From the Vienna Woods. He scored Paul Thomas Anderson's films Hard Eight (1996) and Boogie Nights (1997); he also appears in the latter in a cameo role playing Nick, a recording Engineer. During the editing of the film, Anderson directed a music video with Penn for "Try" from Resigned (the video can be found on the Boogie Nights DVD). Other films scored by Penn include Alan Cumming's first two directorial efforts, The Anniversary Party and Suffering Man's Charity; American Teen, Sunshine Cleaning; the documentary The Comedians of Comedy; and The Last Kiss. In 2003, he was nominated for a DVDX Award for Best Original Score in a DVD Premiere Movie for Melvin Goes to Dinner.

Penn met fellow singer-songwriter Aimee Mann, and during the recording of her album I'm with Stupid (to which Penn contributed), the two struck up a friendship, which blossomed into romance and their December 29, 1997, marriage. Together with manager Michael Hausman they formed United Musicians, an independent music collective founded on "the principle that every Artist should be able to retain copyright ownership of the work he or she has created and that this ownership is the basis for artistic strength and true independence." Penn and Mann live in Los Angeles.

In August 2005, Penn released Mr. Hollywood Jr., 1947 on his own Mimeograph Records label. Its songs are set against the background of post-World War II Los Angeles; Penn said he chose the year because of several notable events that took place then, including the passage of the National Security Act and the invention of the transistor. The album was reissued by Legacy Recordings in April 2007 with bonus tracks from a KCRW session.

In late 2009, Penn composed the music for the film That Evening Sun.

In 2012 Penn began work as the Composer for the HBO TV show Girls.

He also joined the crew of Showtime's Masters of Sex in 2013 as series Composer. The show's pilot episode was initially set to be scored by Thomas Newman, but this did not come to fruition and Penn scored both the pilot and the rest of the series.

In 2018, he joined two new TV series as a Composer - Good Girls on NBC and Here and Now on HBO.