Cathal Joseph Smyth was born on 14 January 1959, in Middlesex Hospital, Fitzrovia, London, England, and grew up in Marylebone. As a child he went by the name of Carl. His parents were Irish immigrants. His father worked in the oil business and moved the family from Ireland to England, and then to the Middle East because of his work. The Smyths were competitive Irish dancers, and Cathal grew up around dance, but never took much of an interest until he began to dance as a performer.

In 1976, the North London Invaders recruited Smyth to play the bass guitar with them when he was only 17 years old, but he was replaced a year later by Gavin Rogers. During the late seventies, Cathal became friends with members of the band Madness, and performed as a dancer onstage at their concerts.

In 1980, Smyth became the last of the seven original Madness members to join the band. He soon moved on to playing other instruments instead of bass. After Madness broke up in 1986, he formed a new short-lived band The Madness in 1988 along with Suggs, Lee Thompson and Chris Foreman.

In 1990, Cathal became an executive for Go Discs where, at his suggestion, the label signed The Stairs. He was also responsible for reforming Madness in 1992 for Madstock!, but he left Go Discs to reform the band. In 1989/1990, he became friends with former Smiths singer Morrissey, who had once asked him to be his manager. Smyth declined, claiming that “I didn’t fancy having to iron his socks.” Smyth introduced Morrissey to Boz Boorer, who went on to work with him from 1991 onwards. Cathal is also the subject of the 1992 Morrissey single, “You’re the One for Me, Fatty”.

He also provided backing vocals on Morrissey’s version of the Jam’s “That’s Entertainment”. Cathal also had a small part in Suggs’ solo career, co-writing the song “Green Eyes,” and he also performed backing vocals on The Lone Ranger album. In 1999, Smyth formed and fronted the folk-influenced band The Velvet Ghost, which played at the Fleadh festival in 2000.

In 2002, Cathal started up his own record label, Rolled Gold Records (RGR Music), at an office in Camden Town. He released a debut single, “We’re Coming Over”, with The England Supporters Band (billed as Mr. Smash & Friends) and it reached number 67 in the UK Singles Charts. RGR released an album and three singles by London rapper, Just Jack. The label also released material by dance and rap artists Autamata and Border Crossing. In 2004, after briefly moving his office to Islington, he closed RGR.

After being a couple since their teen years, Smyth and his wife of 28 years, Joanna Brown, separated in 2005. He has three grown-up children from the marriage: Caspar, Milo, and Eloise. He appeared with Eloise at the 2012 Q Awards ceremony.

After his marriage ended, Smyth started to practise Transcendental Meditation. He also spent time in rehab in Arizona and moved to Ibiza in 2008.

In 2009 Madness released their first album of new material in ten years, The Liberty of Norton Folgate. About this time, Smyth was rumoured to be working on several solo projects, including a dubstep album, according to Mojo. In 2012 Madness followed up “Norton Folgate” with Oui Oui, Si Si, Ja Ja, Da Da.

His debut solo album, A Comfortable Man, was released in May 2015 and it reached no.68 in the UK album chart. In 2016 Madness released Can’t Touch Us Now, the first Madness album since One Step Beyond to be recorded without Smyth being credited as a member of the band.