After attending Gearradh na Monadh school, Campbell left Uist for secondary school in Oban, where he developed a keen interest in literature under the expert guidance and encouragement of his English teacher, the late Iain Crichton Smith. The University of Edinburgh beckoned, where he obtained an Honours degree in History and Politics, and continued his literary education through the encouragement of the late Sorley MacLean, Writer in Residence in Edinburgh at the time.

A career in journalism followed, initially working with the West Highland Free Press, and afterwards with the BBC and Grampian Television. He has also had various occupations as a film actor Angus Peter Campbell, kitchen-porter, forester, lobster fisherman and builders' labourer.

In addition to two Scottish Gaelic poetry collections, he has written two Gaelic novels. An Oidhche Mus Do Sheol Sinn (The Night Before We Sailed), published in 2003, was his first novel for adults, and in 2005, it held the eighth position in The List Best 100 Scottish Books Ever Poll as voted by the Scottish public. His second Gaelic novel, Là a' Deanamh Sgeil Do Là (Day Speaketh Unto Day) was published in 2004. In 2006, his first English fiction, Invisible Islands was published. It was inspired by Italo Calvino and Jorge Luis Borges. The book consists of twenty-one chapters, each illuminating a specific island in the mythic Invisible Islands archipelago. The work draws heavily on Gaelic culture and history, magic realism and a number of other influences.

Campbell has also been awarded several literary prizes, including both the Bardic Crown and a Creative Scotland Award in 2001.

In 2006 Campbell expanded his acting career, starring in the Scottish Gaelic feature film The Inaccessible Pinnacle.

His favourite writers are Leo Tolstoy, George Eliot, Gabriel García Márquez and Italo Calvino.

Campbell lives on the Isle of Skye with his wife and six children, and is now a full time writer with a position at Sabhal Mòr Ostaig.