The Hollywood Reporter said Betty Sue died Monday near her mother's ranch in Hurricane Mills.
Loretta Lynn's representative issued a statement to the entertainment industry trade newspaper saying the recording artist is grateful to her friends and fans for their thoughts and prayers.
Betty Sue was the eldest of the 81-year-old singer's six children with her late husband Oliver.
The couple's son Jack Benny Lynn drowned in 1984. He was 34.
2014: The Year in Music [PHOTOS]