The Ecuador international returns to Liga MX having made the move to Europe with the Hammers in 2014 following one season at Pachuca.
Valencia made an encouraging start to his top-flight career, scoring a cracker against Hull on his full debut, but injuries hampered his progress at the east London club.
The 27-year-old forward spent last term on loan at Everton, where he found the back of the net just three times in 21 league outings.
He did not feature in Hammers boss Slaven Bilic's future plans upon his return to the capital and has headed back to Mexico.
"West Ham United can confirm that Enner Valencia has joined Mexican Liga MX club Tigres UANL for an undisclosed fee," read a statement on the club's official website.
"The 27-year-old departs east London after three seasons, during which he scored ten goals in 66 appearances in Claret and Blue.
"West Ham United would like to thank Enner for his efforts and wish him all the best for his future career."