The plea agreed between the former Liverpool midfielder's lawyers and the public prosecutor in December, was formally processed in a hearing that lasted barely 10 minutes.
The prosecution alleged Mascherano failed to declare over 1.5 million euros in earnings between 2011 and 2013 by ceding his image rights to companies he owns in Portugal and the United States.
Mascherano admitted to the two counts of tax fraud against him in October and deposited nearly 1.75 million euros with the tax authorities in September to repay the amount owed plus interest.
"I'm very relieved to know I am back in line," Mascherano said in a statement published on his official Twitter account.
"I am a professional sportsman, I don't have great knowledge of tax and legal matters. Therefore, I have to rely on people that manage these technical issues.
"During my whole career I have been honest and responsible, respectful to my teammates and the clubs I have represented and the countries I have lived in."
Mascherano's club and international teammate Lionel Messi faces similar sanctions as he is due to stand trail for tax fraud on May 31.
The recently crowned five-time World Player of the Year and his father have been charged with allegedly failing to declare 4.16 million euros in taxes related to his image rights between 2007 and 2009.
Unlike Mascherano, Messi hasn't admitted to any crime, insisting it was his father Jorge Horacio who managed his finances, which makes a similar plea with the authorities less likely.