Ross Ulbricht has been found guilty of creating and running the Silk Road drug-dealing website.
The jury of six men and six women took just 3.5 hours to come to the conclusion that Ulbricht, 30, was the man behind the pseudonymous owner of Silk Road, known as Dread Pirate Roberts.
Ulbricht was found guilty on all counts, which included narcotics trafficking, computer hacking, money laundering, conspiracy to traffic fraudulent IDs and engaging in continuing criminal enterprise. He will be sentenced on 30 May and could face between 20 years and life in prison.
During its two-year life, Silk Road - which could only be accessed through the anonymous Tor web browser - grew to become the biggest illegal drug market on the internet, allegedly earning its owners millions of dollars in commission.
Lyn Ulbricht, Ross' mother, said she "assumes" Ross will appeal the guilty verdict, and that evidence indicating there was more than one Dread Pirate Roberts was not allowed. She said their lawyer was "shackled" by the judge's decision to not hear evidence from three of the defence's witnesses.
"You can't get the full picture when you cherry pick evidence," Mrs Ulbricht added.
Ulbricht's defence said the 30-year-old created Silk Road, but found running the site "too stressful after a few months, and he handed it off to others."
Joshua Dratel, Ulbricht's lawyer, said his client was lured back into running the website after its owners found out an FBI raid was imminent. Dratel described Ulbricht as the perfect "fall guy."
But a detailed diary found on Ulbricht's laptop revealed his plans for the website, as did written notes found by FBI agents in his bedroom.
The trial's closing arguments saw the prosecution claim Ulbricht ran the Silk Road website from its creation in early 2011 to its closure by the FBI in October, 2013. Prosecutors describe the Texan as a power-hungry kingpin who used threats of violence and murder to protect his multimillion-dollar drug empire.
Silk Road "was his baby, and he stayed with it enthusiastically for nearly three years," assistant US attorney Serrin Turner told the court. "It was his secret livelihood. It was his passion."