Nominally a full-back, the Spain international has become accustomed to playing on the right-hand side of Conte’s preferred backline, alongside David Luiz and Gary Cahill.
The former Osasuna player could make his 200th appearance for Chelsea against Sunderland on Wednesday, having joined from Marseille in 2012.
“I’m really happy to have signed a new contract,” he told the club’s official website.
“Since I arrived here my target was to progress as a player and win trophies. This new contract gives me the chance to continue my relationship with the club, that’s what I wanted and obviously I’m really happy here.
“We’ve had some really good moments so far this season. From day one, we started working very hard. We have a new manager with new ideas and I’m really happy to be working with him. Obviously we can still improve but the long-term aim for us is to win trophies, that is what we all want, the players, manager and fans.”