The hacking scheme he ran from 2008 to 2014 targeted US pizza chains in Washington state.
The jury in the trial found him guilty on 38 out of 40 charges including fraud and ID theft.
Seleznev, who is the son of a Russian MP, will be sentenced on 2 December and faces a mandatory jail term of four years.
Prosecutors called Seleznev "one of the most prolific credit card thieves in history" who stole and sold almost 3 million credit card numbers.
To carry out the hacking scheme, Seleznev hacked into point-of-sale systems in pizza restaurants and then installed malware that siphoned off copies of credit card numbers. The lists of numbers were then sold on net markets where stolen information is traded. More than 3,700 businesses were hit by the hack attacks, said prosecutors.
Seleznev pleaded not guilty.
US Secret Service agents arrested Seleznev and his girlfriend at a Maldives airport in 2014.
Lawyers acting for the hacker said they planned to appeal against the conviction. The appeal will seek to challenge what his legal team described as his "illegal arrest" in 2014 as well as a separate ruling that let the government use evidence from a corrupted laptop seized when he was arrested.
"If Roman was Canadian, this case would never have happened," Seleznev's lawyer John Henry Browne told the Wall Street Journal. "There was definitely politics involved in this."
Russia has also lodged official complaints about Seleznev's seizure and extradition saying it pointed to a campaign by US authorities to "hunt" Russians all over the world.
The US Department of Justice said Seleznev "was prosecuted for his conduct not his nationality".
Russian Roman Seleznev has been found guilty in the US of running a hacking scheme that stole $169m (£131m).