Janowski passed speedway licence test (Licencja "Ż") on 7 August 2007 at 16 years old; 5 days later he rode in his first meeting in Polish Ekstraliga (Wrocław vs Rzeszów 48:42). In his first heat, he beat Rzeszów' rider Andreas Messing from Sweden.[2] His fourth meeting was Tournament of Junior National Team Reservs (Turniej zaplecza kadry juniorów). In this meeting he was 4th.[1] He has won qualification to U-19 Bronze Helmet Final; Janowski was 13th (he was only 16 years old). With Atlas Wrocław he started in European Club Champions' Cup Final - Janowski scored 5 points, but Atlas was last.
In 2009, he rode for Atlas Wrocław in Poland, Rospiggarna in Sweden and MSC Diedenberge in Germany.[5] In Sweden, he rode in nine matches and scored 4.52 point per match.[6] Janowski was unsuccessful in defending his Under-21 Polish Champion title, scoring 8 points and finished eighth. However, he did win the Bronze Helmet Final, at his home track in Wrocław, scoring a maximum 15 points. On 25 September he was second in Silver Helmet Final, losing to Grzegorz Zengota by two points.
Like his Rospiggarna Hallstravik team-mate, Greg Hancock, Janowski moved to Piraterna Motala before the 2010 season.[6] On 18 August, it was announced that Janowski would join the Swindon Robins in the British Elite League for the remainder of the season. Maciej won the 2010 Polish Under-21 Championship, held in Toruń, scoring a 15-point maximum. Maciej is also riding in the U21-World Cup and was 2nd beating the main rival Maksim Bogdanows in Pardubice.
A second World Cup winners medal came his way at the 2017 Speedway World Cup, he topped scored for Poland in the final, as the team finished eight points ahead of Sweden.
In 2023, he was part of the Polish team that won the gold medal in the 2023 Speedway World Cup final, his last lap overtaking of Robert Lambert sealed the title for Poland and it was a third World Cup success for Janowski.[11] However his individual season ended with a disappointing 14th place finish in the 2023 Speedway Grand Prix.
He returned to ride in Britain after signing for the Oxford Spires and in Sweden for Piraterna for the 2024 season.[12]
Family
His parents are Piotr and Beata. He has two brothers Wojciech and Krzysztof.[1]