Chaffin won two track championships at the historic Nashville Speedway USA during his career in regional competition. He also competed part-time in the IHRA Stock Car Series. His NASCAR career began in the Busch Series in 1993.
Chaffin made his NASCAR debut in a 1993 Busch Series race at Rockingham, driving the No. 16 31-W Insulation Chevrolet and posting a 29th-place finish. Through the 1990s and into the mid-2000s he made sporadic Busch Series appearances, primarily in the No. 16 and No. 77 cars for various teams including Day Enterprise Racing and Team Rensi Motorsports. His most active Busch Series season was 2002, when he made 26 starts from the 34-race schedule, achieving a best finish of 12th at Talladega. Over more than eighty career Busch Series starts, Chaffin recorded one top-ten finish.
Chaffin found his most competitive results in the Craftsman Truck Series. He made his series debut in 2000 and returned in 2001, in both years racing with Long Brothers Racing and posting a best finish of fourth. For the 2003 and 2004 seasons he drove the No. 18 Dickies Dodge for Bobby Hamilton Racing, achieving a career-best tenth-place points finish in each of those two years. He also recorded two race victories in 2004, winning at Dover International Speedway and Indianapolis Raceway Park.
In 2005, Chaffin drove for three different teams across 21 of the season's 25 races, beginning with Germain Racing before moving to Wyler Racing and then making a single start for ThorSport Racing. He continued in the series part-time through 2008, primarily in the No. 40 Key Motorsports Chevrolet, totaling two top-ten finishes in 22 combined starts over those final two seasons.
Chaffin made four Cup Series starts out of fourteen attempts between 2004 and 2007. His debut came at Martinsville in 2004 in the No. 98 MACH 1 Motorsports Ford, where he completed 100 laps before a mechanical failure ended his day in 39th. In 2005 he qualified for the Checker Auto Parts 500 at Phoenix with Front Row Motorsports, finishing 43rd due to overheating. His 2006 season included time across three Front Row Motorsports entries — the Nos. 34, 61, and 92 Oak Gloves Chevrolets — as he moved within the organization across the year. In 2007 he joined R&J Racing but was replaced before qualifying. He later made a Cup attempt at Loudon that year, qualifying after a disqualification created an opening, and made his way in.
Chaffin's sole ARCA appearance came in 2000 at Daytona with his own Chaffin Motorsports entry, the No. 92 Upstate Helicopters Ford. He qualified third for the Pro2Call 200 but retired on lap ten with a transmission failure, finishing 40th.
Chad Chaffin's career exemplifies the class of NASCAR journeymen who competed across all series levels without the backing of top-tier equipment, carving out victories and results through determination and adaptability. His two Craftsman Truck Series wins at Dover and Indianapolis Raceway Park in 2004 remain the highlights of a career defined by perseverance rather than resources.