Barnett was born in the
Horseshoe Hills, north of
Manhattan, Montana. He was the son of Joseph William and Francis () Barnett, and he was orphaned by the age of eight. He was raised in Manhattan, and attended
Montana State College, earning a bachelor's degree in physical education. He married Janelle Stitt in 1949, and they remained married until her death in 2021. He served in the
U.S. Air Force, then was hired by
Bozeman High School in 1956 as a history teacher and coach, earned a master's degree in administration from Montana State, and taught until 1984. In 1963, he and his wife purchased a beekeeping business, which would grow into his fulltime profession. He died at his home in
Belgrade, Montana, on January 5, 2025, at the age of 95. ==Electoral history==