Mainer grew up listening to traditional mountain music and was largely influenced by his brother-in-law Roscoe Banks. He first learned to play the banjo at square dances, where he would pick up instruments left by performers and practice on them. After moving to Concord, North Carolina and working in a series of jobs at cotton mills, he became a part of his brother J.E.'s band, known as J. E. Mainer's Mountaineers. His entry into the band in 1934 marked the beginning of a nearly six-decade career in music. J.E. played the fiddle while Wade performed on the banjo for the string band, and they played at fiddlers' conventions and other gatherings.