He embarked on a solo career in 1975 and had global success with "All by Myself", "Never Gonna Fall in Love Again", "She Did It", "Hungry Eyes", and "Make Me Lose Control".

By the time he was a sophomore at Charles F. Brush High School, Carmen was playing piano and singing in rock bands including the Sounds of Silence.

[7] Though classically trained in piano, at age fifteen, Carmen started to take guitar lessons, but when his teacher's approach did not fit with what he wanted, he decided to teach himself.

[9] Cyrus Erie guitarist Wally Bryson had been playing with friends Jim Bonfanti and Dave Smalley in one of Cleveland's most popular bands, the Choir, which scored a minor national hit in 1967 with the single "It's Cold Outside".

[10] When Cyrus Erie and the Choir disbanded at the end of the 1960s, Carmen, Bryson, Bonfanti, and Smalley teamed up to form the Raspberries, a rock and roll band that was among the chief exponents of the early 1970s power pop style.

[9] In 2004, Carmen, along with original Raspberries members Jim Bonfanti, Wally Bryson, and Dave Smalley, re-formed the band for a series of sold-out live performances in cities across the United States.

On that tour, the Raspberries recorded a live album of their hits at the House of Blues on Sunset Strip, in West Hollywood.

[14] The follow-up single, "Never Gonna Fall in Love Again"[6] – based on the main theme of the third movement of Rachmaninoff's Symphony No.

Those two songs featured on his 1975 self-titled debut album, along with "That's Rock and Roll", a number 3 hit single for singer Shaun Cassidy.

[21] In 1985, Carmen resurfaced on Geffen Records with a second self-titled album and a sizable comeback hit, "I Wanna Hear It from Your Lips".

[6] "Reason to Try", a further contribution to the One Moment in Time compilation album of songs recorded for the 1988 Seoul Summer Olympics, kept Carmen's profile high in 1988, during which the nostalgic "Make Me Lose Control" also returned him to the number one position on the Adult Contemporary chart – where it stayed for three straight weeks – as well as number 3 on the Billboard Hot 100.

[6] Following a final minor chart hit in 1988 with "Reason to Try", from an Olympics-themed compilation album,[23] Carmen's career was largely inactive for a decade.

The album did not find a large audience, but Carmen continued to enjoy success placing songs with other artists over the years.

[25] Carmen was married three times: to Marcy Hill from 1978 to 1979; to Susan Brown, with whom he had two children, from 1993 to 2009; and to former newscaster Amy Murphy from 2016 until his death in 2024.