He made his pan-European karting début in 2006, competing in the Rotax Max Euro Challenge for the AGS Racing team.

While completing his career in karts, Korjus also spent 2008 adjusting to single-seaters, competing in the first Finnish Formula Renault championship.

[6] On April 17, 2011 he became the youngest driver to win a race in Formula Renault 3.5 Series – at 18 years 3 months and 8 days – with his victory in Monaco in 2008.

Korjus endured a difficult season, with a string of early retirements and mechanical problems that affected his qualifying performances, though he recovered to finish on the podium in the second race at the Moscow Raceway.

Korjus had his first outing in a Formula One car at the Abu Dhabi young driver test on November 16, 2011, driving a Renault R31.

In 2014, he moved to sports car racing, driving an ART Grand Prix McLaren MP4-12C in the European Le Mans Series.