Miguel is the only Portuguese rider currently racing in the top category. He began his professional career in 2011, competing in the 125cc championship. His best result that season was a 7th place finish in Estoril. He achieved six top 10 finishes throughout the year but was unable to race the final events due to team issues.

In 2012, he joined Estrella Galicia 0.0 in Moto3, teaming with Alex Rins. That season, he finished 8th in the World Championship, after securing two podiums: second in Australia and third in Catalunya.

In 2015, riding for the Red Bull KTM Ajo team, he claimed his first Moto3 win, becoming the first Portuguese rider in Championship history to do so. That year was meteoric for Miguel, as he also won in Assen, Aragon, Australia, Malaysia, and Valencia, secured three second places in Spain, San Marino, and Japan, and claimed a pole position in Argentina. He ended the season 2nd in the championship, just 6 points behind the champion.

In 2016, he moved to Moto2 with the Leopard Racing team, but it was a transitional year, with his best result being 8th at the Catalunya GP.

In 2019, Miguel signed with the MotoGP Red Bull KTM Tech 3 team, a satellite team of KTM. As a rookie, he finished in the points in nine out of the sixteen races he contested, with his best result being eighth in Austria. He was also the best KTM finisher in that GP. However, in the British GP, he suffered a shoulder injury in a collision with his teammate Johann Zarco, which was aggravated by a crash during free practice sessions at the Australian GP. Oliveira was unable to race in the Grand Prix, bringing his season to an early end.

Fully recovered, in 2020, he secured two historic wins in his home country: at the Styrian GP and the Portimao GP.

In 2022, Miguel reconnected with Estrella Galicia 0.0, with the brand returning as one of his sponsors and establishing a close collaboration. That year, he stood out as a wet-weather specialist, winning two races in Indonesia and Thailand, under torrential rain.

In 2023, the Portuguese rider changed teams, joining the RNF MotoGP Team, supported by Aprilia. However, an injury in the opening round at the Portimao GP and another at the Jerez GP ruined the first half of his season, with his best result being a fifth place at Silverstone.

In 2024, with Trackhouse Racing, he suffered another injury, missing five more Grand Prix, finishing 15th in the Championship.