The 30-year-old, who is a product of the club's youth system, has signed a two-year contract extension, meaning that he will now remain with Athletic until the end of June 2020, reports Xinhua news agency.
His previous deal had been due to expire at the end of June 2018.
Benat has made 120 league appearances for Athletic, as well as another 49 in other competitions and also played 75 times for the club's B-team.
But it was at a spell with Betis that he began to produce his best form, winning four Spain caps and earning a return to Athletic in the summer of 2013.
His new deal includes a 50 million euros (nearly $60 million) buyout clause, but it now looks likely Benat will end his career at the club where he started it.
Athletic will now turn their full attention into persuading Spain goalkeeper Kepa Arrizabalaga to extend his current contract.
The goalkeeper, who recently celebrated his 23rd birthday, is also out of contract at the end of the current season and could leave for nothing unless they are able to persuade him to stay.
(This story has not been edited by Social News XYZ staff and is auto-generated from a syndicated feed.)
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