Hillin was born in Midland, Texas, and grew up in a motorsport environment: his father owned Longhorn Racing, which competed in United States Auto Club-sanctioned sprint and Indy car events. A natural athlete — he was an all-district linebacker in high school — Hillin began driving stock cars at the age of thirteen and quickly won the track championship at Odessa Speedbowl in Odessa, Texas. He attended the Buck Baker Driving School at sixteen, accelerating his development as a professional racer.
Hillin made his Winston Cup debut at seventeen years old, driving a family-owned car crewed by the experienced Harry Hyde in the 1982 Northwestern Bank 400 at North Wilkesboro Speedway, finishing 21st. He relocated to North Carolina to pursue his career full-time, completing his high school education through correspondence courses — he received his diploma the day before the 1983 Coca-Cola World 600.
In 1984 Hillin joined Stavola Brothers Racing. Two years later, on August 3, 1986, he won the Talladega 500 at Talladega Superspeedway at the age of 22 years, 1 month, and 22 days, setting the record as the youngest winner in NASCAR's modern era. The victory placed him on the national radar, but Hillin later acknowledged that he lacked the maturity to manage the expectations and pressures that followed such an early breakthrough.
He added two wins in the NASCAR Busch Series in 1988 and 1989, driving for Highline Racing, but his Winston Cup results did not replicate the Talladega high. He departed Stavola Brothers after the 1990 season.
The 1991 season proved a turning point. Hillin qualified the backup car for Moroso Racing fastest in third-round time trials for the Daytona 500, then turned in a seventh-place finish in the race itself, earning the team's primary seat. Sponsorship shortfalls curtailed the schedule after ten races, and Hillin was released. He drove two races for Jimmy Means Racing before stepping in as substitute driver for Kyle Petty, who had broken his leg in an accident at Talladega. Hillin completed eight races in the Team SABCO No. 42 until Petty's return.
From late 1991 into 1992 Hillin drove for Team Ireland, then moved to Donlavey Racing for the full 1993 season. After a partial 1994 campaign that saw stints with Charles Hardy Racing and Moroso Racing, he joined Jasper Motorsports twelve races into 1995, replacing Davy Jones. He remained with Jasper through 1996 and most of 1997, also taking part in the Suzuka Thunder Special — an exhibition race at Suzuka Circuit in Japan following the 1996 season — where he finished seventh. He was released from Jasper after failing to qualify for the 1997 Coca-Cola 600, with Morgan Shepherd taking his place. His final Winston Cup start came at Bristol Motor Speedway in 2000, substituting for an injured Stacy Compton at Melling Racing.
On the Busch Series side, Hillin launched his own team for the 1998 season with an ownership group that included five Major League Baseball players. The venture underperformed, and after 2000 he stepped back from full-time competition to focus on business interests in Texas. Brief returns followed — at Kansas Speedway in 2008 and Texas Motor Speedway in 2009, both for MacDonald Motorsports in the Nationwide Series — before he retired from the sport for good.
Bobby Hillin Jr.'s 1986 Talladega 500 victory remains a landmark in NASCAR history as proof that youth alone is no barrier to winning at superspeedway speeds. His career arc — early triumph, mid-career struggles with multiple team changes and funding gaps, and a reflective semi-retirement — mirrors the volatile economics of stock car racing in the 1980s and 1990s. After racing Hillin became CEO of T-Rex Engineering & Construction, a company serving the Gulf of Mexico oil drilling industry.