The 27-year-old has made 99 appearances for Mexico and can play at left-back or on the left wing.

"Andres is a very experienced player and played last season as a regular in Valencia's Champions League team," said Bayer's director of sport Rudi Voeller.

"His versatility means that he fits exactly with our requirements and we are convinced he will boost the team."

Leverkusen, who are second in the Bundesliga behind Bayern Munich, retain the option to buy Guardado when the loan deal finishes.

"The offer for Leverkusen was a great chance for me to start something new," said Guardado.

"The Bundesliga has a great reputation in Spain and it is something special for me to get to know this great league.

"Bayer are a top German team and also in the Champions League, therefore I am really happy that the deal has come off."

Guardado was part of a clean out at Valencia which also saw Colombia's Dorlan Pabon and Portugal's Helder Postiga leave for Sao Paulo and Lazio respectively.