In January 2013, the "Girls VOL.1" soundtrack was released on iTunes. The album contained a new song by Michael Penn titled "On Your Way", which was featured in the finale of Season 1.
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.