Martin was born as the oldest of five children of Anthony and Alison Martin, an accountant and teacher respectively, in Exeter, Devon, England. He was educated at Sherborne School, a famous boys' independent school in Sherborne, Dorset, in England, and later at University College London where he read Ancient World Studies. Martin played the family piano from a young age, and would later learn how to play the guitar.

As a solo artist, Martin has written songs for a variety of acts including Embrace ("Gravity") and Jamelia ("See It in a Boy's Eyes"). Martin has also collaborated with Ron Sexsmith, Faultline, The Streets, and Ian McCulloch. He also sang a part of the vocals for the Band Aid 20 single, "Do They Know It's Christmas?" at the end of 2004. In 2005, Martin collaborated with Nelly Furtado on the track "All Good Things (Come to an End)", for her 2006 album, Loose. The two were once rumoured to be a couple, after they both performed at Glastonbury in 2002. Furtado joked about the situation, saying that "Yeah, he's my boyfriend — he just doesn't know it yet"

Martin's fascination with hip hop was shown in the summer of 2006 when he collaborated with rapper Jay-Z for the rapper's comeback album Kingdom Come after the two met earlier in the year. Martin put some chords together for a song known as "Beach Chair" and sent them to Jay-Z who enlisted the help of hip hop producer Dr. Dre to add the drum line to complete the track. The song was performed on September 27, 2006 by the two during Jay-Z's European tour at Royal Albert Hall. "Beach Chair" is featured on the album Kingdom Come and is rumored to be the third single off the album.

In 2007, Martin appeared on a track titled "Part of the Plan" for Swizz Beatz' debut solo album One Man Band Man. Martin has also worked on a solo collaboration with Kanye West, with whom he shared an impromptu jam session during a 2006 concert at Abbey Road Studios. He performs the chorus on a song called "Homecoming" on Kanye West's newly released album, Graduation.

--Wikipedia