She learned how to drive from her father and she would drive a car around the family farm since she was about 12 or 13 years old. Earnhardt Miller raced stock cars at local tracks. Her father Dale Earnhardt reportedly said that she might be the next great driver from the Earnhardt family because of what ESPN described as her “aggression, mental toughness, a willingness to push the car to its limit”. Her cousin Tony Eury, Jr. said, “She was very good at what she did. I raced her several times over at Tri-County [Racetrack in Brasstown, N.C.]. We thought she probably had as much or more talent than any of them.” She raced more frequently at Hickory Motor Speedway and Myrtle Beach Speedway. Her father hired Dale, Jr. to work on her race cars, including building one from scratch, while the two were local race car drivers. She raced after graduating from University of North Carolina at Charlotte and ended her racing career in 1996 until leaving on Friday’s at 2 o’clock conflicted with working full-time at Action Performance.

She married Raymond Walter Holm Jr. on June 29, 2001 in Mecklenburg County, North Carolina. They were divorced by 2004 in Iredell County, North Carolina.

She was formerly married to Jimmy Elledge, by whom she has two daughters. After divorcing Elledge, she married former NASCAR driver L. W. Miller III on January 22, 2011. The couple has one child.

Kelley’s daughter Karsyn Elledge participates in midget car racing. She scored her first win at Millbridge Speedway on April 19, 2018. Karsyn made her first Chili Bowl start in January 2019.

On July 29, 2019, agricultural company Brandt appointed Earnhardt Miller into the Board of Directors. Brandt is currently one of JR Motorsports’ partners, sponsoring the No. 7 team.

On April 22, 2019, Brenda Jackson, Earnhardt’s biological mother, died at the age of 65 after years of battling cancer. She had served as an accounting specialist for JR Motorsports since 2004.