Beginning his motorsport journey at the age of eight, Alex started racing in the Honda Cadet class and quickly rose through the ranks, winning multiple titles along the way. He became a multiple champion at both the British and European levels, including claiming both the CIK-FIA World Cup and CIK-FIA European Championship in 2010 in the KF3 category.

Alex graduated to single-seaters in 2012, spending a three seasons competing in Formula Renault 2.0 and claiming a best finish of third overall in the 2014 Eurocup category. He subsequently stepped up to the FIA Formula 3 European Championship in 2015, finishing seventh overall and stepping on to the podium five times. A move to the GP3 Series followed for 2016, with Alex narrowly missing out on the title, ending the year runner-up to Charles Leclerc, having achieved four wins and seven podium finishes.

Two consecutive years in FIA Formula 2 saw Alex claim third in the championship in 2018, only beaten by George Russell and Lando Norris. That precipitated a move into Formula One, with Alex drafted into Scuderia Toro Rosso for 2019. A number of eye-catching performances saw him promoted to Red Bull Racing after just 12 races, where he remained for 2020, scoring two podium finishes and finishing the season seventh overall.

For 2021, Alex was named as Red Bull Racing’s Reserve Driver. He combined the role with a full campaign in the DTM, where he finished sixth overall.

In 2022, Alex took on the role of Race Driver for Williams Racing, marking his third season racing in Formula One. During the 2022 season, Alex impressed the team with stand-out performances, including his debut points-scoring race in Melbourne, in addition to placing 9th in Miami and 10th in Belgium.

Williams Racing announced during the 2022 season that Alex will remain part of the driver line-up for the 2023 FIA Formula One World Championship and beyond.

Alex had a standout 2023 season finishing 13th place in the Drivers' Championship scoring 27 points and helping the team secure seventh place in the Constructors' Championship. He made the top 10 seven times in grands prix with impressive P7 performances in Montreal and Monza and scoring in the Qatar sprint race.

2024 marks Alex's third year racing for Williams Racing, alongside American driver Logan Sargeant.