Allison came up through the same modified stock car circuits that produced his brother Bobby, racing in the rough-and-tumble short-track world of the American South before graduating to the Grand National level. Like many drivers of his era, he built his craft on dirt and asphalt ovals far from the superspeedways that would later define his reputation.
Allison earned his first NASCAR Cup win at the 1968 Carolina 500 at Rockingham Speedway and his tenth and final victory at the 1978 Dixie 500 at Atlanta Motor Speedway. He was named the 1967 NASCAR Grand National Rookie of the Year, an early marker of his talent in a deep field.
His career was curtailed by serious injuries sustained at the 1981 Coca-Cola 600. Though he attempted a return, Allison completed only fourteen more Winston Cup starts between 1982 and 1988, also failing to qualify on four occasions. The injuries effectively ended his front-line competitive years.
Allison is perhaps most indelibly remembered for the climactic final lap of the 1979 Daytona 500, which was the first NASCAR race broadcast live flag-to-flag on national television by CBS. Allison was leading on the final lap with Cale Yarborough drafting close behind. As Yarborough attempted to pass on the inside, contact was made — Yarborough struck Allison from behind, sending Allison sideways. The two cars traded contact multiple times before locking together and crashing into the outside wall in turn three.
As both stricken cars came to rest in the infield grass, Bobby Allison pulled up to check on his brother. Yarborough, convinced Bobby had contributed to the incident, confronted him while he was still seated in his car, and a fight broke out involving all three men. Richard Petty, running more than half a lap behind the crash, inherited the lead and won the race.
The incident — the wreck, the confrontation, the brawl — played out live on national television and became one of the defining moments in NASCAR history. The drama attracted massive media attention and is widely credited as a turning point in the sport's growth into a mainstream American entertainment property.
Allison also demonstrated his versatility by competing in USAC Championship Car events. In the 1970 Indianapolis 500, driving the No. 83 Eagle 67-Offenhauser for Ansted-Thompson Racing, he finished fourth and won the 1970 Indianapolis 500 Rookie of the Year Award. The following year he returned to the 500 in the No. 84 Purolator Filters Coyote-Ford V8, finishing sixth. Because he held a NASCAR license rather than a USAC license during these appearances, he was ineligible for USAC points standings in both seasons.
Following his competitive career, Allison worked as a television and radio commentator and served as a consultant to his sons' racing operation, Allison Brothers Race Cars, as well as the Allison Legacy Race Series. Among the up-and-coming drivers he advised were Joey Logano, Trevor Bayne, Regan Smith, and John Hunter Nemechek.
Allison accumulated an extensive list of honors across his career, including induction into the Alabama Sports Hall of Fame (1999), the Florida Sports Hall of Fame (2000), the Stock Car Racing Hall of Fame (2001), the International Motorsports Hall of Fame (2009), the Motorsports Hall of Fame of America (2011), and ultimately the NASCAR Hall of Fame (2024). He also received the Talladega-Texaco Walk of Fame honor and the 1967 NASCAR Most Popular Driver award in the Grand Touring Division.