U.S. Attorney Preet Bharara said Friday more than 144,000 bitcoins were found on computer hardware belonging to Ross William Ulbricht.
Federal authorities in New York have charged Ulbricht with three felonies related to the operation of the website. He was sent to New York from California earlier this month.
The federal public defender who represented Ulbricht in California declined to comment. His New York attorney didn't immediately return messages.
Silk Road gained notoriety as a black market bazaar where drugs could be bought and sold using bitcoins, a form of online cash.