Behzad Mesri is accused of accessing a computer without authorisation for the purposes of commercial advantage.
Court documents allege he had worked for Iran's military and been involved in a campaign to deface US websites
They allege he began conducting online reconnaissance of HBO's computer networks and employees in May 2017.
"Over the next couple of months, he successfully compromised multiple user accounts in order to obtain access to the media giant's servers," the documents say.
"Through the course of the intrusions into HBO's systems, Mesri was responsible for stealing confidential and proprietary data including... scripts and plot summaries for unaired programming, including but not limited to episodes of Game of Thrones."
A few weeks later, the documents allege, Mr Mesri claimed to have stolen about 1.5TB of data and began an extortion campaign that included an email to HBO employees that read: "Hi to All losers" Yes it's true! HBO is hacked!"
It is unclear whether any ransom money, demanded in Bitcoin according to the court documents, was ever paid.
A Department of Justice press conference is due to be held at 17:30 GMT.
It is not known how the accused will plead.
Photo copyright: HBO. Caption: The leaks were released prior to the broadcast of Game of Thrones series seven episodes