Johnston's rally career began at the age of sixteen. At the
2019 Wales Rally GB, he made his WRC debut by co-driving with
Oliver Solberg in a
Volkswagen Polo GTI R5 in the WRC-2 category. Both Johnston and Solberg were signed by
Hyundai Motorsport to compete for the
2021 World Rally Championship-2. On 16 September 2021, Johnston and Solberg announce their split after 3 years of collaboration. Just five days later on 21 September, Johnston announced he would partner Japanese driver
Takamoto Katsuta for the
2021 Rally Finland, replacing the injured
Daniel Barrit. ==Rally victories==