Team changes

• LCR Honda expanded to enter a second bike for the first time since 2015.[15]
• Aspar Racing Team will race under the name of "Ángel Nieto Team" from 2018 in honor of the late Ángel Nieto.[27]

Rider changes

• Sam Lowes was released from his contract with Aprilia Racing Team Gresini one year before it expired.[28] Lowes returned to the Moto2 category.
• Thomas Lüthi moved up to MotoGP, making his début with EG 0,0 Marc VDS after competing in the intermediate class for eleven seasons.[18]
• 2017 Moto2 champion Franco Morbidelli was promoted to MotoGP, making his début with EG 0,0 Marc VDS.[19]
• Esteve Rabat returned to Reale Avintia Racing, after leaving EG 0,0 Marc VDS. He was partnered by Xavier Siméon who moved up to the premier class. Rabat previously competed with Avintia Racing under the name By Queroseno Racing (BQR) between the 2005 125cc and the 2011 Moto2 seasons.
• Takaaki Nakagami moved up to MotoGP with Team LCR.[15]
• Scott Redding left Pramac Racing at the end of the 2017 season to join Aprilia Racing Team Gresini.[2] His place was taken by Jack Miller.[12]
• Loris Baz left MotoGP and returned to Superbike World Championship.
• Héctor Barberá returned to the intermediate class, Moto2, after leaving Reale Avintia Racing. Barberá has completed eight seasons in the premier class.
• Jonas Folger, who was on the provisional entry list, withdrew from the 2018 season to focus on recovery from illness.[29] Hafizh Syahrin moved up to MotoGP to fill his spot in Monster Yamaha Tech 3. He is the first Malaysian rider to compete in the sport's premier class.[30]