The defender arrived at Stamford Bridge from French club Marseille in 2012 and has since made 95 appearances for the club in all competitions, scoring his only goal against Arsenal in last season's League Cup.
Azpilicueta kept long-serving left-back Ashley Cole out of the Chelsea first team for much of last term and now has a firm grip on the position following the Englishman's departure for Roma during the close-season.
Part of the Chelsea side that lifted the UEFA Europa League trophy in 2012-13, Azpilicueta went on to win the club's Players' Player of the Year award last season.
Having made two appearances for Spain at the World Cup earlier this year, he is currently part of Vicente del Bosque's squad for Thursday's friendly against France and the Euro 2016 qualifier against Macedonia four days later.
Azpilicueta, who can also play right-back, faces competition from Filipe Luis following his arrival from Atletico Madrid.
The 25-year-old's next appearance in a Chelsea shirt will likely come in the home Premier League fixture against Swansea City a week on Saturday.
