Zhou started karting at the age of eight years old in China before moving to the UK in 2012 for a more competitive racing environment. He won both the Super 1 National Rotax Max Junior and Rotax Max Euro Challenge in 2013, beating Formula 1 driver Lando Norris. During his final year of karting, Guanyu finished second in Rotax Max Senior Euro Challenge and participated in a selected rounds of the WSK Champions Cup and the KF2 European Championship.
For the 2015 Italian F4 Championship, Zhou joined Prema Powerteam. With his consistent podium finishes, he ended the season as vice-champion and best rookie, beating both Robert Schwartzman and David Beckmann. Alongside his successful debut to the Italian F4 Championship, Zhou competed in selected rounds of the German ADAC F4 Championship, bagging himself two podium finishes in Spielberg and Spa.
In 2016, Zhou made his debut into the FIA Formula 3 European Championship by joining team Motopark. His season started off successful in Paul Ricard and Hungaroring by finishing in 2 podium positions before struggling during the second half of the season, only managing to finish 13th.
Zhou stayed for his second F3 season by rejoining Prema and improved to 8th, claiming five podium finishes. A lot of speculation surrounded Zhou for his 2018 plans with a possible move to FIA F2 however, he took on his third F3 season and remainded with Prema. He received a win in Pau followed by a podium in Hungaroring and three consecutive podium finishes in Zandvoort, Guanyu was second with only a point between himself and team mate Marcus Armstrong. Although he was looking strong, Zhou suffered four consecutive retirements before winning his second F3 race in Hockenheim and finishing the season in 8th.
FIA Formula 2 Championship
Zhou joined UNI-Virtuosi Racing in December 2018 alongside team mate Luca Ghiotto to compete in the 2019 FIA Formula 2 Championship. He achieved a maiden feature race podium in Barcelona after leading the majority of the race before dropping to third. He achieved third in the Monoaco sprint race after overtaking Artem Markelov at the start, a third place at Paul Ricard and also scored his first F2 pole position at Silverstone, becoming the first Chinese driver to do so.
For the 2020 season, Zhou has remained with UNI-Virtuosi alongside team mate Callum Ilott, who competed with Sauber Junior in the 2019 FIA F2 Championship.