He is best known for co-writing and performing the main theme song of the NBC sitcom Cheers, "Where Everybody Knows Your Name".
In the early 1980s, Gary Portnoy and Judy Hart Angelo set out to write a theme for Cheers.
Portnoy also wrote several songs for the NBC television series Fame, including the Emmy-nominated track for Best Original Song, "I Still Believe In Me" (co-written by Susan Sheridan) as well as "It's Gonna Be a Long Night" (co-written by Estelle Levitt).
In 2003, after a hiatus from the music business during the 1990s, Portnoy released the 12-track album Keeper, which includes the full-length version of "Where Everybody Knows Your Name".
It includes Portnoy and Hart Angelo’s three initial attempts at composing the theme as well as their songwriting demo and subsequent full-length recording of "Where Everybody Knows Your Name".