The 22-year-old has signed a five-year deal at La Mestalla after whirlwind talks with club president Jaime Orti.
The African ace agreed to join Valencia after holding talks in Barcelona before flying out to his native Cameroon
Eto'o was widely expected to leave San Moix this summer after a superb season last term in which he scored twice in the Copa Del Rey win over Recreativo.
The former Real Madrid star had attracted interest from a number of clubs including Liverpool, Manchester United, Marseille, Lyon and Parma.
Eto'o was believed to favour a move away from La Liga, but Valencia have persuaded him to stay in Spain.
Valencia coach Rafael Benitez had made Eto'o his top summer transfer target as they look to make up for last season's disappointing season which saw them miss out on Champions League qualification.
The fee for Eto'o is unknown, but the player is thought to have been offered a lucrative contract which will increase after every year.
