Ratthapark Wilairot finished 10th as a wildcard at the Japanese GP in 2006 before entering the World Championship full time via the 250cc class in 2007 as a member of the Thai Honda PTT SAG team. He placed 17th in his first full season, then 13th in his next two seasons. Taking on Moto2™ in 2010, Wilairot came agonisingly close to a first ever GP podium at Assen, battling to the end before finishing fourth. In 2011 he continued with the SAG team, riding an FTR chassis, after recovering from a serious off-season motorcycle accident. The Thai rider changed teams for 2012 as he took on the Moto2 category once again, this time as a member of the Gresini Team, with which he stayed for 2013. For 2014, he left Moto2™ to compete in the Supersport World Championship with PTR riding a Honda CBR600RR. He started the 2015 season with the Core Honda team, winning his home race in Thailand, before making a return to the Moto2™ World Championship with the JPMoto Malaysia team in time for the Catalan Grand Prix, as a replacement for Zaqhwan Zaidi. JPMoto Malaysia and Wilairot parted company after four rounds, but the Thai rider found himself back in the Moto2™ championship in 2015 with Idemitsu Honda Team Asia on a Kalex.