Betis president Manuel Ruiz de Lopera confirmed the decision after a meeting with manager Victor Fernandez regarding adjustments to the Betis squad for next season.
The Seville-based outfit will have to pay around ‚é¼3 million (£2 million) to complete the deal after an agreement signed between the two clubs last summer.
Alfonso has suffered an injury-plagued term this year making only 13 starts in the league, managing six goals.
Despite this, Ruiz de Lopera insists that the Spanish international has merited the move.
"Alfonso deserves the chance to continue in the team because the green and white (of Betis) are in his heart," said the Betis supremo.
