Ippei Mizuhara was officially sentenced to 57 months in prison on Thursday ... after fessing up to swindling millions from Dodgers superstar Shohei Ohtani.

Mizuhara's fate was determined in a Santa Ana, California court just minutes ago -- not only has he been sentenced to four years and some change behind bars, but he was also ordered to pay $18 million in restitution -- nearly $17 million to Ohtani and another $1.1 million to the IRS.

The former Angels and Dodgers employee pleaded guilty to one count of bank fraud and one count of tax fraud back in June 2024 ... owning up to taking the money from Ohtani's bank account to clear his debts with bettors.

He was facing up to 33 years in prison ... but the plea agreement likely helped shorten his sentence.

Mizuhara expressed his regret over his actions again in court ... saying it was a mistake that would stick with him for the rest of his life, but was prepared to accept the consequences.

Mizuhara's attorney was pulling for an 18-month sentence due to his accountability and remorse ... but ultimately, federal prosecutors got what they wanted.

Mizuhara was ordered to surrender on March 24.