Born in Cushing, Oklahoma, his full name is Samuel Kent Harris. He was brought up in Sand Springs, Oklahoma. He left home at the age of 15 to pursue his career. He finished high school through correspondence courses while performing in Nashville and working with Nashville Repertory as an actor.
When 18 he moved to Los Angeles and attended UCLA to study theatre. While at UCLA he met Bruce Newberg and they wrote the musical Hurry! Hurry! Hollywood! which was produced by UCLA. During his second year at UCLA he won the Frank Sinatra Pop Vocal Award. This prompted him to drop out of his studies after only two years and to pursue his singing.
In 1983 Sam Harris and Bruce Newberg collaborated on producing the pilot television sitcom Down to Earth. The show went on to run for four years on the cable television station TBS. When 22 he became grand champion of the first season of Star Search and hence became a household name and attracted the attention of the music business. His song was Over The Rainbow which became a signature song for him.
His first album Sam Harris was released in 1984, and the single Sugar Don't Bite had moderate success reaching 36 on the Billboard charts. His second album Sam I Am was released late in 1985 and featured many original songs written by Sam Harris and his brother Matt Harris.
In 1989 Sam Harris won Drama Logue Awards for writing and acting in Hard Copy which ran for six months in Los Angeles. During 1990 to 1992 he starred in productions of Jesus Christ Superstar, Joseph and the Amazing Technicolor Dreamcoat, and Cabaret. He also had his concert debut in London.
In 1993 he was on the London stage again. In 1994 he starred in Grease which progressed to Broadway, and he received excellent reviews. In 1997 he received acclamation for his performance on Broadway in The Life for which he received numerous nominations including a Tony nomination.
He began to talk publicly of being gay in the late 1990s.