In 2013, Smith won the bandoleros national championship, claiming victories at Atlanta, Charlotte, and Bethel Motor Speedway. He enrolled at Pickens High School in Jasper, Georgia, graduating with the class of 2020. His father, Mike Smith, owns Smith General Contracting, a business that became a primary sponsor supporting Chandler's early racing career.
Smith made his ARCA Menards Series debut in 2018 at Nashville Fairgrounds Speedway, winning the pole after qualifying was rained out and leading 51 laps before finishing fifth. In his fourth ARCA start, he dominated at Madison International Speedway to record his first series win. A second win followed at Salem Speedway in September 2018.
He returned to Venturini Motorsports part-time in 2019 and 2020, running mostly short-track events due to age restrictions at the larger tracks. In 2020, ten of his races were part of the inaugural Sioux Chief Showdown within the ARCA Series.
Kyle Busch Motorsports (KBM) gave Smith his Truck Series debut in 2019 with a four-race schedule. At Iowa, his first Truck start, he captured the pole and led the opening 55 laps before finishing eighth. He returned to KBM part-time in 2020 before being promoted to a full-time schedule in 2021, driving the No. 18 Toyota for KBM.
His 2021 season featured a pivotal moment at Bristol, where Smith won in a must-win playoff situation, beating Grant Enfinger and narrowly avoiding elimination. He also won at Phoenix before finishing eighth in the standings. In 2022, also at KBM, Smith won at Las Vegas and Pocono during the regular season, then added another victory at Richmond in the playoffs to make the Championship 4. He finished third in the standings and third at the Phoenix championship race.
Smith ran part-time in 2023 and 2024 before rejoining the Truck Series full-time with Front Row Motorsports for 2025, driving the No. 38 Ford. He won at Bristol and North Wilkesboro in his first season with the team and opened the 2026 campaign with a win at Daytona.
In October 2022, Kaulig Racing announced Smith would replace A.J. Allmendinger in the No. 16 Chevrolet for the full 2023 Xfinity season. He scored his first Xfinity win at Richmond, but parted ways with the team at the end of the year. He then joined Joe Gibbs Racing in a deal that reportedly saw JGR buy out his remaining Kaulig contract. In 2024, driving the No. 81 Toyota for JGR, Smith won at Phoenix and Richmond, but was eliminated in the Round of 8 at Martinsville. He was also fined $10,000 for slapping Cole Custer in a post-race altercation. Smith parted ways with JGR at season's end.
Smith attempted the 2023 Daytona 500 for Kaulig Racing but failed to transfer from the qualifying Duels, finishing eighteenth in Duel 1. He made his official Cup Series debut at Richmond that year, finishing seventeenth. Subsequent Cup attempts came through MBM Motorsports and Front Row Motorsports, where he ran the No. 36 Ford on a part-time basis.
Smith married Kenzie Grams on July 17, 2021. They have a son, Chandler Smith Jr., born August 4, 2022, and announced a second child in May 2023.