A former taxi cab driver Parsons became an Automobile Racing Club of America (ARCA) hero winning the ARCA Championship in 1968 and 1969.

In 1970 Parsons switched to NASCAR's Winston Cup racing circuit, and that same year finished in the top 10 a total of 23 times out of 45 races.

He was the NASCAR Winston Cup Series champion in 1973. His championship season was one of endurance in that he won only one race (second-place finisher Cale Yarborough won four times in the 28-race season and David Pearson won 11 times but ran only 18 events) but drove the most miles. Two of his biggest wins came at the 1975 Daytona 500 and the 1980 Coca-Cola 600 at Charlotte (N.C.) Motor Speedway. Parsons was the first NASCAR Winston Cup competitor to qualify for a race faster than 200 mph, which he did for the 1982 Winston 500 at Talladega (Ala.) Superspeedway with a speed of 200.176 mph.

Throughout his racing career Parsons was a consistent top finisher. Between 1965 and 1969 he won 16 ARCA races. In NASCAR he won 21 Winston Cup races and 20 pole positions, placed in the top five 199 times and placed in the top ten 283 times. Parsons is the only driver to win both the ARCA and the NASCAR Winston Cup Championships.

In 1988 Parsons retired after 526 career NASCAR starts to become a full-time broadcaster and maintain his own automotive parts business.

In 2006, Parsons was diagnosed with lung cancer, which was reported to be in full remission. He entered Carolinas Medical Center in Charlotte on December 26th suffering complications that arose from his lung cancer battle.

Sadly Parsons lost his battle on January 16, 2007 at the Carolinas Medical Center in Charlotte, N.C.