Raffaello Follieri - who dated 'The Devil Wears Prada' actress for four years before they split in June 2008 - was sentenced to four-and-half years behind bars in October 2008 after pleading guilty to charges of wire fraud, money laundering and conspiracy.
But he has now completed his time in federal prison in Loretto, Pennsylvania, but because he is not a US citizen, he will be deported back to his native Italy as soon as he is released.
In 2008, Follieri admitted in court he had "no excuses" for his illegal actions.
Hesaid: "The most important thing I want the court to know is I was not raised with bad values. I started off with good intentions, determined to run an honourable business and make everyone proud of me.
"What I did was wrong and there is no point in making excuses. I will never be able to wash away the shame. I just hope that someday those who have been hurt by my actions will forgive me."
Follieri was arrested in June 2008 after he was found to be lying to potential investors, saying he was a member of the Vatican, and then using the money to travel to the Dominican Republic on holiday with Hathaway.
He was also found guilty of using the money to pay his $37,000-a-month rent, medical bills for both him and Anne, and his father's orthodontist bills.
Anne is now engaged to Adam Shulman.