Randle grew up in Australia and began his motorsport career in karting, winning the Junior Clubman class of the Australian National Sprint Kart Championship and the Rotax Junior class of the Australian Rotax Nationals in 2012. He has studied Mechanical Engineering as a university student and runs a business called Dream Simulation that helps drivers develop skills across racing categories. In January 2020 he was diagnosed with testicular cancer, an experience that framed his championship season that same year.
Randle made his single-seater debut in the 2013 Australian Formula Ford Championship for Evans Motorsport Group, finishing seventh with two podiums. He switched to Dream Motorsport in 2014 and clinched the championship title with five race wins, edging Jordan Lloyd by four points.
He remained with Dream Motorsport for the 2015 Australian Formula 4 Championship but finished runner-up to Lloyd by 54 points and five wins. In 2016 he moved to Europe, competing in the BRDC British Formula 3 Championship for Douglas Motorsport, winning races at Rockingham and Spa and finishing fourth in the standings. He also made a single Formula V8 3.5 appearance that year at Jerez with Comtec Racing. In 2017 he contested the Eurocup Formula Renault 2.0 with AVF by Adrian Valles, scoring points in nine of his sixteen races with a best result of fourth at the Red Bull Ring, finishing fourteenth overall. That same season he won the Toyota Racing Series in New Zealand.
Randle joined the Dunlop Super2 Series in 2018 with Tickford Racing in a Ford FG X Falcon. He progressed through the development series, winning the 2020 Super2 Series championship with Tickford to earn his promotion. He was awarded the Mike Kable Young Gun Award in 2018, the BRDC Innes Ireland Trophy in 2020, and the Peter Brock Medal in 2023.
He was unable to find a Super2 ride for 2021 and competed in the Australian S5000 Championship with Team BRM before Tickford confirmed his promotion to the main series.
Randle began his full-time Supercars Championship career in 2022 with Castrol Racing under the Tickford umbrella, finishing 21st in his rookie season. His 2023 campaign marked a breakthrough: he claimed his first podium finish in Race 20 at The Bend (third), then secured his first pole position the following day in Race 21, converting it to a second-place result. He finished 2023 with four podiums overall.
Away from racing, Randle plays volleyball and piano. He appeared on the ABC television program The Piano in 2025 as a contestant. His cancer diagnosis in January 2020 preceded his Super2 Series championship win later that year, a sequence that drew considerable attention to his resilience in competition.
Randle's pathway through three separate single-seater championships, a European Formula 3 campaign, a Super2 title, and eventual Supercars Championship podiums illustrates the depth of technical development he brought to his career. His success in the 2020 Super2 Series during a period of personal health difficulty added a layer of public recognition that extended beyond his results.