Rhett's "Die a Happy Man" beat out "Humble & Kind" by Tim McGraw, "My Church" by Maren Morris, Chris Stapleton's "Nobody to Blame" and Record Year by Eric Church to claim the ceremony's first honour, reported Contactmusic.
McGraw was celebrating minutes later after his "Humble & Kind" hit was named Song of the Year.
Stapleton was already a winner before the prize giving began at the Bridgestone Arena after claiming the Music Video of the Year title for "Fire Away."