Moss was born and raised in Los Angeles. He grew up surrounded by the theatre, concert, and rock & roll music world. At age 11, he started learning to play the drums, guitar and electric bass. In 1976, Moss joined creative forces with fellow singer/guitarist Peter Beckett, guitarist/keyboardist J.C Crowley, and Drummer John Friesen to form the band Player, primarily as Bassist and singer. In a garage in the Hollywood Hills, they wrote and rehearsed the music that would soon attract the attention of music impresario Robert Stigwood, who signed them to his RSO Records.

In the first three weeks of 1978, their single "Baby Come Back" occupied the #1 position on the national pop charts & Player was voted to the Billboard Magazine honor roll of Top New Singles Artist of 1978. Their follow-up single, "This Time I'm in It for Love,", also peaked at No. 10 the same year.

Moss played the Saracen hero Ruggero who fell in love with Bradamante in the 1983 Italian film Paladini-storia d'armi e d'amori (aka Paladins—the story of love and arms, aka Hearts and Armor) – a film based on the legends surrounding the Peers of Charlemagne.

1987 also marks the year of Moss' most critically acclaimed theatrical role as Rowdy Abilene in the Andy Sidaris classic Hard Ticket to Hawaii.

The Australian edition of his 2002 solo CD “I’m Your Man” includes a fresh duet of the original hit "Baby Come Back" & two bonus tracks, "That's When I'll Be Gone" & "Mountain". Moss along with his band toured Australia between August and September 2006. In 2007, he released his 2nd solo album, Uncovered.

Moss has a large fan base in Australia. In 2006, a campaign surfaced to vote Moss as Australian of the Year. Moss was featured in a very popular television commercial for Berri, an Australian orange juice Producer. The punchline of the advertisement was "you can tell when it's not all Aussie"— a line intended to show (in jest) that, while Moss has longstanding connections with Australia, his Hollywood career has resulted in his persona differing significantly from that of the cliché Australian male. He has appeared occasionally on the former program Rove Live when in Australia. He takes part in sketches that are parodies of the daytime TV genre.

The Bold and the Beautiful was a very popular prime-time show in much of Europe; in 2010, Moss was a participant in the Italian version of Dancing with the Stars, finishing second with his partner Sara Di Vaira.

On August 11, 2012, it was announced that Moss would exit The Bold and the Beautiful, after having played the character of Ridge Forrester for 25 years.

On May 12, 2014, Moss, along with his band Player, appeared on the ABC daytime soap opera General Hospital as part of the 2014 Nurses' Ball, where they performed their hit single "Baby Come Back".

As of 2015, he plays the character of Ian in the Flemish soap Familie.