The former Liverpool midfielder has reached an agreement over a new contract, committing his future to the Blaugrana for the next four years
The versatile Argentine midfielder, who can also play at centre-back, has developed into a key player at the Catalan club since completing a €22 million transfer from Liverpool.
He has now added two years to his previous deal, which expired in 2014, to put an end to all speculation surrounding his long-term future at Camp Nou.
Meanwhile, Barca have also revealed that Mascherano's release clause is now set at €100m.
The 28-year-old has made 97 appearances for the Blaugrana, although he has yet to break his duck in front of goal.