Yamaha Factory Racing has announced a 'Sponsorship and Partnership agreement' with Monster Energy for the 2013 and 2014 MotoGP seasons.
Monster branding will be visible on the YZR-M1s and leathers of Jorge Lorenzo and Valentino Rossi as well as team clothing and equipment.
However it is not a full title sponsorship agreement - as exists between Monster and the satellite Yamaha Tech 3 team - since the team name remains 'Yamaha Factory Racing'.
Reigning MotoGP champion Lorenzo - previously backed by rival energy drink Rockstar - has a personal engagement with Monster and Yamaha included in the new agreement.
Rossi's existing deal with Monster will be complementary to the new Yamaha deal.
Monster's title sponsorship of Tech 3 'will remain unchanged and is unaffected'.
Lin Jarvis, managing director of Yamaha Motor Racing, said: “We are very happy to be able to announce the start of a new chapter in the Yamaha – Monster Energy partnership.
"Monster Energy is already a major partner to Yamaha's top global sports activities in many domestic and international racing activities around the world in Motocross, Supercross, Endurance and Superbike disciplines.
"They have also been the title sponsor of the Monster Energy Tech 3 Yamaha team for the past 4 years. The expansion to include the Yamaha Factory Racing MotoGP Team is a logical and prestigious expansion of the program.
"This completion of the program permits Yamaha and Monster Energy to work even closer together to develop their sports marketing programs and to develop rider talent to continue to be successful into the future in all areas of motorcycle racing."
The Factory Yamaha team has not had a title sponsor since Fiat left, with Rossi, at the end of 2010.
Bradley Smith and Cal Crutchlow will race for Tech 3 this season.