He was ordered to pay back nearly $17 million (£13.6 million) he stole from the star athlete and another $1 million in back taxes to the US Internal Revenue Service (IRS).
Mizuhara, who had been Ohtani's English interpreter since his Major League Baseball (MLB) debut in 2018, was fired last year after media reports about his gambling activities sparked an investigation into Ohtani's finances.
The investigation found that Mizuhara stole nearly $17 million from the athlete to pay off a loan from a Southern California bookmaker.
He then lied on his tax records to cover up his activities. He pleaded guilty to bank and tax fraud charges.
"Mr. Mizuhara held a unique position of trust that gave him power, fame and a good salary," said Acting U.S. Attorney Joseph McNally. "Unfortunately, he used this dream job to steal millions of dollars from his friends and confidants."
"This is a sad tale of an American success story gone wrong - so wrong that Mr. Mizuhara will spend years in prison."
Sitting in a courtroom in Santa Ana, California, Mizuhara wore a light black suit, his hands in his lap, and looked directly at the judge as he announced his verdict.
He remained motionless during the sentencing.
Before the sentencing, he apologized for his actions.
"I am truly sorry for what I did to Mr. Ohtani. I know that an apology will not make up for my crime," he said. "This mistake will affect me for the rest of my life, and I am prepared to accept the consequences."
The scheme threatened to destroy the career of Ohtani - currently one of baseball's biggest global stars - as questions were raised about whether he was involved in gambling.