In 1982 he joined Richard Childress Racing to become the crew chief for Dale Earnhardt. Earnhardt had 46 wins, 142 top 5 finishes, and 246 top 10 finishes with Shelmerdine en route to four championships in 1986, 1987, 1990 and 1991. The pit crew won four consecutive Pit Crew Titles over the next eight years. His accomplishments include being the youngest crew chief to win a NASCAR race, and the youngest crew chief to win a Winston Cup championship. In 1992, he announced he was retiring from his crew chief duties, and embarked on a racing career on his own to pursue his dream of being a driver.

He started running in the ARCA series in 1993 where he has three career wins. He has since run in all the top levels in NASCAR. Shelmerdine has run a total of two Craftsman Truck Series races with a best finish of 17th at Bristol in 1995. He has also run 12 Busch Series races with a best finish of 17th in 1994 at Daytona for Levin Racing.

Shelmerdine's Nextel Cup career actually started in 1981 in a race at College Station (Texas World Speedway, where owner/driver James Hylton brought out a 2nd car (No. 8) for Shelmerdine to drive. After two laps, he quit and finished 33rd of the 34 cars. His next start would come at Talladega Superspeedway in 1994 for Jimmy Means. Shelmerdine finished 26th in the No. 52 Ford. He started his own Cup team in 2002 and ran races at Talladega, Loudon and Pocono, but he was primarily a "field filler" driver.

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