Composing since the late 1970s, his songs have been recorded by many Irish artists including Christy Moore, Mary Black, Finbar Wright, Maura O'Connell, the Corrs and Westlife. "Ride On", recorded by Christy Moore, is one of his best-known compositions. Moore also recorded MacCarthy's songs "Missing You", "Bright Blue Rose" and "Mystic Lipstick". Mary Black, Maura O'Connell and The Corrs have recorded MacCarthy's "No Frontiers", while Black has also recorded his songs "Katie", "Adam at the Window", "Diamond Days", "As I Leave Behind Neidín", "Shuffle of the Buckled" and "Another Day." MacCarthy also co-wrote Westlife's "Angel's Wings." This track was meant to be a Christmas single for Westlife during that year but the band chose a different song. MacCarthy believes that if Westlife had released "Angel's Wings" as a single the chances were that it could have become a number one hit and that it would have been nice to have a song at the top of the UK charts. More recently MacCarthy's songs have been recorded by newer artists such as the Celtic Tenors, Michelle Lally, Marc Roberts, and Tommy O'Sullivan. According to a discography site MacCarthy's music has been described as folky power-pop, but it can also be classed as folk-rock. Prior to embarking on a lengthy career as a singer/songwriter in Ireland, MacCarthy released his first single "Miles of Eyes" in 1981 under Mulligan Records. The same year a second single was put out through the same label, which was titled "Like in the Movies". This was after being in a band called "Southpaw" with Declan Sinnott in the late 1970s. A longtime fan of the Beatles, in October 1999 MacCarthy played at the National Concert Hall, Dublin as a special guest with the "fifth Beatle" George Martin. He performed a cover of the Beatles' song "She's Leaving Home". In his career MacCarthy has toured with De Dannan and worked with producers such as Donal Lunny and many more. Up to 2010, MacCarthy released four albums of his own. "The Song of the Singing Horseman" (1991), "The Dreamer" (1994), "The Moment" (2002) and "Hey Ho Believe" (2010).