Lou began his career in porn and became a success with Le Salon Studio's biggest-selling video in Weekend Workout (1987). In 1989, he won an adult film industry award as Best Actor for the title role of Billy Blue in Sexy Billy Blue. In 1990, he formed his own company, Forrest Films, producing, directing, and occasionally guest-starring in films which included The Private Home Videos of Lou Cass, The Private Lives of Lou Cass, Pleasure Theater (for which he also did the soundtrack) and Made in China. Catalina's Man of the Year, was his last appearance in a gay porn video, co-starring Joey Stefano. Clips from Cass's films were used after his retirement in the compilation videos The Best of Joey Stefano and Oral Extravaganza.

He then retired from adult films and began a successful career as a mainstream film and television actor and recording artist. Lou has become the biggest adult film star to crossover into mainstream television and films.

Shortly following his retirement from porn, Lou began his forays into the mainstream entertainment business. His first role was on the popular daytime soap opera General Hospital. His first movie role was playing one of Nick Mancuso's hired guns in the direct-to-video action flick The Takeover in 1994. This was followed by an appearance on Disney film, I Love Trouble, with Nick Nolte and Julia Roberts, and appearances on Melrose Place, Beverly Hills 90210, Picket Fences, The Adventures of Brisco County, Jr., Dr. Quinn, Medicine Woman, seaQuest DSV and an episode of L.A. Law, among others.

In 1990, Lou recorded a compact disc single, Rated X, which became the first recording by a male porn star to hit the Billboard charts. A performance of Lou's single at the I-Beam in San Francisco was quickly sold out. He later performed the single for Bill Graham's In Concert Against AIDS, opening for Grateful Dead, Linda Ronstadt and Huey Lewis & the News

Lou has performed over fifty concerts to raise funds for AIDS research. His first few chart hits were tailored for dance clubs. Some reviewers compared his 'Hi-NRG sound' to the Pet Shop Boys and Madonna. Lou, now sporting many tattoos that cover most of his body, has changed his sound from dance music to a hard-core punk sound, like Black Flag, Henry Rollins and metal rocker Andrew W.K.