Hamilton was orphaned of his custodial grandparents — Preacher Hamilton, a car builder and crew chief for country star Marty Robbins at Nashville Fairgrounds Speedway, and Annie Mae Hamilton — when he was thirteen years old. He quit school at fourteen and began racing at Nashville Speedway USA, the legendary Fairgrounds Speedway. He won back-to-back Late Model Stock Car championships there in 1987 and 1988, and in 1988 achieved the remarkable feat of winning four races across three different divisions in a single night at that track. He came to broader NASCAR attention after a special "Superstar Showdown" at Nashville in 1988 that brought him into direct competition with established Cup drivers Sterling Marlin, Darrell Waltrip, and Bill Elliott.
Hamilton entered the Winston Cup ranks through an unusual path: he drove one of the stunt and movie cars for the 1990 Hollywood film Days of Thunder, qualifying fifth at the 1989 Autoworks 500 in Phoenix. His movie car, a No. 51 Exxon-sponsored Chevrolet, was depicted in the film as driven by the fictional character Rowdy Burns.
Hamilton made his Busch Series debut in 1988 at Charlotte, followed by a full Busch season in 1989 with Filmar Racing, where he won his only career Busch race at Richmond International Raceway. He joined Tri-Star Motorsports for the Cup Series full-time from 1991, finishing second in the 1991 Rookie of the Year standings.
After a season with SABCO Racing in 1994, Hamilton moved to Petty Enterprises in 1995 to drive the iconic No. 43 STP Pontiac. He posted ten top-tens in 1995 and in 1996 won his first Cup race at Phoenix International Raceway in the Dura Lube 500 — the first victory for the No. 43 and for Petty Enterprises since Richard Petty's final win in 1984, ending a 12-year drought for one of NASCAR's most celebrated organisations. He finished ninth in the 1996 points standings, a career best. He won again for Petty at Rockingham in 1997.
Hamilton then joined Morgan-McClure Motorsports in 1998 and delivered one of his most dominant performances, leading 378 of 500 laps at Martinsville Speedway from the pole to win. That season he finished tenth in points. He moved to Andy Petree Racing in 2001 to drive the No. 55 Square D Chevrolet. At the Talladega 500 in April 2001 — the first superspeedway race held since Dale Earnhardt's fatal crash in February — Hamilton won a historic caution-free 500-mile race. The physical and emotional demands of leading the sport's return to a superspeedway left him visibly exhausted; he slumped to the ground after climbing from his car and received oxygen from a tank before giving his victory lane interview from a seated position, leaning against the car door.
He sustained a broken shoulder late in the 2002 season, missing several races. Combined with financial instability at Petree Racing, the injury prompted Hamilton to exit the Cup Series.
Hamilton shifted focus to the Craftsman Truck Series, driving for his own team, Bobby Hamilton Racing. In his first year on the circuit he won twice in the No. 4 Dana Dodge Ram, finishing sixth in points. The following season, 2004, he won four times and clinched the Craftsman Truck Series championship — the first owner-driver to claim a NASCAR title since Alan Kulwicki's 1992 Winston Cup championship. In doing so Hamilton also joined Ken Schrader, Terry Labonte, and Mark Martin as drivers to have won races in all three of NASCAR's top national series (Cup, Nationwide, and Truck).
At Atlanta Motor Speedway in March 2006, Hamilton disclosed publicly that he had been diagnosed with head and neck cancer discovered during the removal of an infected wisdom tooth. His son Bobby Hamilton Jr. took over the No. 18 truck for the remainder of the 2006 season. Hamilton underwent chemotherapy and radiation at Vanderbilt University Hospital in Nashville and made gradual progress through mid-2006, returning to his shop and attending races as his health allowed. However, cancer returned to his neck in late 2006 and required renewed chemotherapy. Bobby Hamilton died on January 7, 2007, at his home in Mt. Juliet, Tennessee, surrounded by family.
Bobby Hamilton's career spanned the unusual arc of an undiscovered short-track prodigy who entered NASCAR's highest level through a film production, eventually winning at the sport's most historic venues and restoring one of its most iconic car numbers to victory lane. His 2001 Talladega win carries enduring cultural weight as the first post-Earnhardt superspeedway race, marking the sport's attempt to move forward under the heaviest emotional circumstances in its history. His 2004 Truck Series title as an owner-driver added a further chapter to a career built on resourcefulness and resilience.