Marklund grew up connected to rallycross through his family's team, Marklund Motorsport, which gave him an early foundation in the sport and a consistent technical base to develop from. Rallycross — combining circuit-style asphalt or gravel tracks with short, intense heats and finals — requires a specific blend of wheel-to-wheel racecraft and car control, and Marklund developed both by progressing steadily through the category ranks from the TouringCar class upward.
Marklund entered five rounds of the 2011 European Rallycross Championship for Marklund Motorsport, driving a Ford Fiesta in the TouringCar class and scoring a third-place finish in Sweden. In the full 2011 European Rallycross Championship he scored two wins and six second-place finishes in TouringCar, claiming the class championship — his first major title.
For the 2013 European Rallycross Championship, Marklund stepped up to the Supercar category, driving a Volkswagen Polo. The jump from TouringCar to Supercar — the top class in rallycross, featuring highly modified cars producing around 600 horsepower — is significant, and his seventh-place championship finish in 2013 reflected a competitive entry-level season at that level.
Marklund made his FIA World Rallycross Championship debut in 2014 with Marklund Motorsport, again in a Volkswagen Polo Supercar. He reached five finals over the course of the season, including a career-best second-place finish in Canada. Scoring points at every event, he finished sixth in the championship — a strong debut in what was the highest tier of international rallycross.
In 2015, Marklund switched to Mattias Ekstrom's EKS RX team, which ran Audi S1 machinery. He drove the Audi at all events except Canada, where he returned to a Volkswagen Polo. The season started badly — a roll at the Portugal season opener and a launch contact incident involving Daniel Holten in Sweden set the tone early. However, Marklund recovered strongly in the second half of the year, taking a sixth place in Turkey and a fourth place in Italy. Alongside his World RX campaign that year he also participated in the Audi Sport TT Cup, finishing sixteenth in the standings with a best result of eighth.
For 2016, Kristoffersson Motorsport and Marklund Motorsport merged their World RX operations under the combined Volkswagen RX Sweden banner. Driving a Volkswagen Polo Supercar, Marklund finished thirteenth in the championship standings, with fourth-place results at Belgium and Sweden as his best performances.
Marklund left the World Rallycross Championship after 2016 and returned to the FIA European Rallycross Championship for 2017 with Marklund Motorsport. The move proved decisive. He dominated the Supercar class with three victories from five rounds, securing the European championship title. The 2017 title validated his development through TouringCar, World RX, and back to European level, confirming him as one of the standout names in European rallycross over the decade.
Marklund's career illustrates the trajectory of a driver who used consistent family-team backing to build technical knowledge and competitive experience across different class levels and teams. His 2017 European title, combined with his competitive World RX record including a race-best second place in Canada, established him as a durable and serious rallycross competitor within a sport that underwent considerable international growth during his career.