Originally from North Carolina, Mainer's main influences came from the mountain music of his family. In a career that began in 1934 and spanned almost six decades, Mainer transitioned from being a member of his brother's band into the founder of his own ensemble, the Sons of the Mountaineers, with whom he performed until 1953, when he became more deeply involved with his Christianity and left the music industry. After working at a General Motors factory and attending gospel revivals, Mainer was convinced that he should restart his career as a Christian gospel musician and began to tour with his wife in this capacity. He continued to release albums until 1993.