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.
In Spain sentences less than two years are normally suspended unless the guilty party has previous convictions.
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.
"I'm very relieved to know I am back in line," Mascherano said in a statement published on his official Twitter account.
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"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 an honest and responsable, respectful to my teammates and the clubs I have represented and the countries I have lived in."
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.
Having arrived from Liverpool in 2010, he found Sergio Busquets well entrenched in his own position of holding midfielder.
It was a simple choice: adapt or fail. So when a spate of injuries left Barcelona without a central defender, he seized his chance.
"I never thought I would be here this long," he said. "I know what I can do, but I also know the demands that Barca places on you. In any other team I would have liked to play in midfield, but changing positions was worth it to keep playing here."
Mascherano plays in midfield for Argentina and is a key player for the side that reached the final of the 2014 World Cup, losing to Germany. His latest positional change for Barcelona goes against a customary trend.
He looked past Roberto's natural replacement, Aleix Vidal, and asked Mascherano to take on the role. Luis Enrique liked the result, so even with Roberto cleared to play against City, he left Mascherano in his place.
Mascherano's industry more than makes up for the fact he has not scored in 290 appearances - a Barcelona club record for an outfield player.
"I am not obsessed over it," he said. "A goal wouldn't change my life."
"My time here at Barcelona has been magical," he said. "Year after year the team has kept its hunger.