The 35-year-old, who is Argentina’s most capped player, will join Estudiantes from Chinese Super League side Hebei China Fortune in 2020.
Mascherano started his career with River Plate but has spent the last 14 years turning out for clubs including Brazil’s Corinthians, West Ham United, Liverpool and Barcelona before moving to China in 2018.
His most successful spell in club football was at Barcelona, where he won five La Liga titles, two UEFA Champions League trophies, five Copa del Reys among other honours.
Mascherano was a member of the Argentina side that lost the 2014 FIFA World Cup final to Germany but has two gold medals from the 2004 and 2008 Olympic games.
Former Argentina international, Juan Sebastien Veron, is the current director of Estudiantes and he travelled to China on Saturday to strike the deal.
"We have travelled 19,000km to welcome Javier to the Pincha family," Estudiantes wrote on its official Twitter account on Saturday, accompanied by a video of Veron and Mascherano dining together in China.
"Estudiantes is your home, Mascherano."
A grinning Veron added in the clip: "We have come all the way to Beijing to see a great friend and a great footballer, Javier.
"Now we are going to have dinner, a big hug to everyone in La Plata."
Estudiantes, who are coached by former Barcelona defender Gabriel Millito, are currently eighth in the Argentina Superliga standings, three points behind leaders Boca Juniors.
