Michelisz began his single-make career in domestic Hungarian championships: he won the 2006 Hungarian Suzuki Swift Cup and followed it with the 2007 Hungarian Renault Clio Cup. In 2008 he competed in the SEAT León Eurocup, winning one race at Monza and finishing fourteenth overall. That result earned a wildcard WTCC entry with the SUNRED Engineering team for two rounds at Okayama. He returned to the León Eurocup in 2009, proved himself the best-scoring driver at the Porto round, and went on to win the championship outright in September. The title converted into a factory drive for SEAT Sport in the 2009 European Touring Car Cup, where he took pole position and won the opening race to finish third in the overall standings behind established names James Thompson and Franz Engstler.
Michelisz joined the WTCC full-time in 2010 with the Zengő-Dension team, racing a SEAT León TDI. He scored his first podium at Okayama following the disqualification of Andy Priaulx and Augusto Farfus, then took his maiden WTCC victory at the Macau season finale. He finished ninth in the championship and won the Rookie Challenge. In 2011 the team switched to a BMW 320 TC; Michelisz again finished ninth, taking a podium at the Hungaroring where he also posted the fastest lap in both races.
He secured his second WTCC win in 2012, triumphing in race two at the Race of Hungary in front of his home crowd. At the end of the 2012 season finale at Macau, Michelisz won the Yokohama Trophy for independent drivers — described at the time as the most significant result in Hungarian motor racing history. When Zengő Motorsport switched to Honda for 2013, Michelisz stayed, winning at Suzuka and later at the Hungaroring in 2015.
On 13 January 2016, Honda announced Michelisz as a factory driver alongside Rob Huff and Tiago Monteiro. In that first factory season he claimed another victory at Suzuka and finished fourth in the championship. In 2017, he emerged as a genuine title contender but was defeated by Cyan Racing's Thed Björk in a dramatic final weekend at the Qatar season finale.
Following the merger of the WTCC with the TCR International Series, which created the World Touring Car Cup for 2018, Michelisz moved to BRC Racing Team to drive a Hyundai i30 N TCR alongside Gabriele Tarquini. He scored one win at Slovakia Ring in 2018, finishing fourth in the championship while contributing to Tarquini's title campaign; Tarquini became the inaugural WTCR champion.
In 2019, Michelisz raised his level substantially. Racing again with BRC and Hyundai, he accumulated five victories and ten podium finishes over the course of the season. The championship was decided at the Sepang finale in a direct fight with Esteban Guerrieri of Münnich Motorsport, driving a Honda. Michelisz prevailed to claim the WTCR title, becoming Hungary's first FIA touring car world champion.
Beyond the WTCR, Michelisz has remained active in the TCR World Tour, winning the series in both 2023 and 2024 and demonstrating his sustained competitiveness well into the second decade of his career at the top of touring car racing.
Michelisz represents the pathway from Eastern European national championships to the highest tier of international touring car competition. His 2012 Yokohama Trophy and the 2019 WTCR championship are regarded as landmark moments for Hungarian motorsport. His consistency across manufacturers — SEAT, BMW, Honda, Hyundai — and across both the WTCC and WTCR eras reflects an ability to adapt to different machinery at the front of the field.