Mascherano, a teammate and close friend of Messi during his playing career at Barcelona and with the Argentina national team, cites personal reasons for leaving after just over a year.
"I would like to thank the club for their faith in me, but above all the players who made it possible for us to experience unforgettable memories," he tells Miami's website.
Javier Mascherano led Inter Miami to its first MLS title last season.
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