Marsh was born in Te Kuiti, New Zealand in 1951 and has Ngāpuhi and Ngati Hine iwi affiliations. He moved to Auckland to pursue a career as a carpenter, but became involved with Christian music, studied theology and lead a youth ministry. In 1984 Marsh became involved with country music and began performing around New Zealand. He won a number of local awards, and eventually release his debut album, For You, in 1989.

Marsh has since released 25 albums, including two which reached #1 on the New Zealand albums chart, four gold albums and six platinum albums. He has won numerous country music awards, including being honoured as the 2011 Country Music Legend at the National Country Music Awards, and inducted into the Golden Guitar Awards Hands of Fame, also in 2011.

In 2013 Marsh hosted the Māori Television country music showcase series My Country Song. This was followed by a compilation album, The Best of My Country Song and a live album, My Country Song – The Showcase Concert, both of which featured songs from Marsh.