Harper O'Neill was born in Bridgerton, Texas and grew up in a musical family. Her parents introduced her to various genres of music, especially country and rock. She learned to play guitar and write songs when she was a child and performed in local festivals and bars. She moved to Nashville in 2018 after graduating from The University of Texas at Austin with a degree in Advertising.
O'Neill signed a publishing deal with Jody Williams Songs, a co-venture with Warner Chappell Music, in 2022 after being discovered on TikTok by former BMI executive Jody Williams . She also won the American Songwriter Song Contest with her song "Somebody", which she co-wrote with Meg McRee. She received a $10,000 prize, studio equipment, a Gibson guitar, and a year of distribution via Play MPE.
O'Neill released her debut single "Guilty" in 2023, which showcased her originality and authenticity as a country artist. She also toured with Ashley McBryde and Morgan Wade as an opening act. She is managed by QPrime South, who also represent Eric Church, Ashley McBryde, and Brett Eldredge. She is currently working on her first album, which is expected to be released in 2024.