At the age of four, he tried karting for the first time and one year later, he took his first win in the Easykart International Grand Final. For the following six years, Robert took many trophies in a variety of different kart events, including taking the Bronze medal in the KF-Junior Karting Championship.

In 2014, Robert made his single-seater debut in the Formula 4 Championship, finishing third the following year with three wins for Mücke Motorsport (twice at Adria and at Misano). He also took part in the SMP Racing programme and that year and again in 2016, he continued to race in the German Formula 4 series, as well as the Eurocup Formula Renault 2.0 and Formula Renault 2.0 NEC where he took two wins for Josef Kaufmann Racing (Nürburgring and Hockenheim). In 2017, he raced in Eurocup Formula Renault 2.0  with the R-ace GP team and came third in the Championship, taking six wins (Monza, Silverstone, Pau Nürburgring and two wins at Barcelona) and seven pole positions.

In 2018, he won the Toyota Racing Series NZ title with M2 competition, with a win in Taupo, before competing in the FIA F3 championship with Prema Powerteam. He was third with two wins (Spielberg and Hockenheim). In 2019, he won the high quality FIA Formula 3 championship with one race in hand, beating his Prema teammate and FDA colleague, Marcus Armstrong. Robert won three times (Race 1 in Barcelona, Race 2 at Le Castellet and Race 1 at Monza.) There were a further seven podium finishes, two pole positions and two fastest race laps.

He made his Formula 2 debut in 2020, taking four wins, the most of any driver and finished fourth in the championship at the wheel of a Prema car. He stayed with the Italian team in 2021 and was in the hunt for the title right down to the final round, fighting team-mate Oscar Piastri. At the end of the season, he drove for both Haas F1 Team and Scuderia Ferrari in the end-of-season test at Abu Dhabi and was confirmed as a test driver for the Scuderia for the 2022 season.