Petty grew up immersed in motorsport. His grandfather Lee Petty won the inaugural Daytona 500 in 1959, and his father Richard accumulated seven NASCAR championships. Rather than pursue college athletics — he had received scholarship offers for both football and basketball at Randleman High School — Petty chose racing. The weight of the Petty name brought both opportunity and enormous expectation from the outset of his career.
Petty made his debut in major-league stock car competition at age eighteen, entering the 1979 Daytona ARCA 200 in one of his father's old 1978 Dodge Magnums. He won the race outright, becoming the youngest driver at the time to win a major-league stock car event. The result announced him as a genuine talent, not merely a legacy entry.
His Winston Cup Series debut came the same year in the 1979 Talladega 500, where he drove a passed-down STP Dodge Magnum numbered No. 42, the number previously used by his grandfather. He ran five races that year and recorded a ninth-place finish in his first series start.
In 1980, Petty made fifteen starts, posting six top-ten finishes and a 28th-place points finish. The 1981 season saw a stronger campaign in his regular No. 42, with ten top-ten finishes and a 12th-place points standing.
From 1982 onward, Petty began to find his footing. He split time between the No. 42 and the No. 1 UNO/STP car in 1982, finishing 15th in points. In 1983, he picked up sponsorship from 7-Eleven and switched his number to 7, finishing 13th in points. Six top-tens in 1984 followed, though he dropped slightly in the standings.
A pivotal move came when Petty joined Wood Brothers Racing for 1985. He produced a then-career-high seven top-five finishes and recorded his first top-ten points finish in the standings. The partnership proved immediately productive.
In 1986, Petty scored his first career Winston Cup win in the Miller High Life 400 at Richmond International Raceway, ending a lengthy search for victory. He finished tenth in the final standings that season. The following year, 1987, brought his second win, the Coca-Cola 600 at Charlotte Motor Speedway, cementing his status as a legitimate front-runner. He drove the No. 21 Ford with Citgo sponsorship in that period, one of the more recognizable liveries of the late 1980s.
The arc of Petty's early career tracks a driver who was competitive but not consistently dominant, working through successive team changes and sponsorship uncertainties common to the era. What distinguished the period was his debut season's extraordinary start, followed by a steady progression toward his first wins at Richmond and Charlotte. The Wood Brothers partnership in 1985–1987 represented the high-water mark of his early career in terms of results and equipment quality.
Petty's lineage gave him access to competitive machinery at the start, driving cars passed down through the family operation, but his transition to outside teams and ultimately his first wins showed he could perform without the immediate Petty Enterprises safety net. By the end of the 1980s, he had moved on to SABCO Racing, where a new chapter would open with different successes and challenges.