Hemric began racing in go-karts at age five at Concord Speedway, winning eleven races and a track championship before progressing through Bandolero and Legends cars. In 2008, he won the back-to-back Legends Pro national championships, and in 2010 he took home the Legends Million at Charlotte Motor Speedway, the largest paycheck in Legends car history at $250,000. He won the Champion Racing Association JEGS/CRA All-Stars Tour championship in 2012 with eight victories, and also captured back-to-back Summer Shootout Series championships at Charlotte.
Hemric made his Truck Series debut at Martinsville in October 2013 before competing full-time with NTS Motorsports in 2015, finishing seventh in the championship and earning a best finish of fourth at three different tracks. In 2016, he joined Brad Keselowski Racing in the No. 19 Ford and posted seventeen top-five finishes without a win, making the Chase as the highest non-winner in points. He returned to the series decades later in 2025, joining McAnally-Hilgemann Racing in the No. 19 Chevrolet, and scored his first career Truck Series win at Martinsville with a three-lap-to-go pass of teammate Tyler Ankrum.
Hemric joined Richard Childress Racing for the 2017 Xfinity season, driving the No. 21 Chevrolet and competing for Rookie of the Year. He advanced to the Championship Round at Homestead as the lone non-JR Motorsports driver that season but suffered battery issues that dropped him thirteen laps behind the leader and left him fourth in the title fight. He returned to the series in 2020 for JR Motorsports on a 21-race schedule, recording twelve top-tens.
In 2021, Hemric moved to Joe Gibbs Racing's No. 18 Toyota. He did not win during the regular season but qualified for the playoffs on consistency, locking into the Championship 4 alongside Austin Cindric, A.J. Allmendinger, and Noah Gragson. At the season finale at Phoenix, Hemric completed an overtime pass of Cindric on the final lap to win both the race and the championship — his first career NASCAR win came simultaneously with his first title. At the time, his ten runner-up finishes before the win tied him with Dale Jarrett for the most in Xfinity Series history.
Hemric drove for RCR's No. 8 in the 2019 Monster Energy Cup Series, earning 2019 Rookie of the Year honors despite finishing 25th in the championship. He drove for Kaulig Racing part-time in 2022, recording a twelfth-place finish at the Daytona 500. He drove the No. 31 for Kaulig full-time in 2024, returning to Cup after five seasons away, before transitioning back to the Truck Series in 2025. A notable off-track moment occurred at the 2022 championship race, when Hemric stepped in for the grieving Ty Gibbs in the No. 23 23XI Racing car after Gibbs had to miss the event following the death of his father Coy Gibbs.
Hemric's 2021 Xfinity championship, secured with a late-race pass and zero regular-season wins, stands as one of the more dramatic title outcomes in series history. His path through grassroots short-track racing in North Carolina, through Truck Series development, and eventually to a NASCAR championship reflects the traditional ladder progression of the sport's modern era.