Casey Mears started his racing career in the Dayton Indy Lights Series in 1999 and finished second in the overall standings that year. He continued his winning ways in 2000 where he won the Grand Prix of Houston. The son of former Indy car and off-road driver Roger Mears and the nephew of Hall of Fame Indy car star Rick Mears, Casey comes from a great family of open wheel racers. Casey also competed in five CART races from 2000 through 2001, posting a fourth-place finish in his series debut at California Speedway in 2000. In 2001, he scored two top-five finishes in four CART starts after replacing the injured Alex Zanardi.

Casey went full-time to stock cars in 2002 where he scored a top-10 finish in his first stock car event, the ARCA RE/MAX Series at Talladega. He then moved on to the Busch Series driving for Welliver-Jesel and finishing 21st in the Busch Series standings by scoring one top-five and two top-10 finishes that season. His results were good enough to get him a job in NASCAR's elite series, taking over driving duties for the No. 41 Dodge for Chip Ganassi Racing where he finished 35th overall in his first season. His top finish was a 15th-place effort at Las Vegas.