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".

Saturday's 28-20 loss at Worcester Warriors kept the Falcons pinned to the foot of the table, and was the fourth defeat of the new campaign.
London Irish have also yet to record a win, but have better points difference.
"We're a much better side than that, there's far more to come out from us," Richards told BBC Newcastle.
"We haven't quite got our attack sorted out yet and our defence is all over the place - if we got one of those sorted out it wouldn't be a problem.
"The defence was woeful in the first half and oddly we won the second half 3-0, but I'm frustrated more than anything."
Saturday's game was the first in which all of the World Cup duty players had been available, with Argentina centre Juan Pablo Socino restored to the starting line-up.
However, not even his introduction helped, as errors continued to plague the Falcons' attempts to end their pointless run.
"At half-time it was about getting it right and understanding where we had gone wrong defensively - which was one-on-one tackles and a few ill-discipline issues, such as lifting the leg in the line-out five metres from their line," said Richards.
"Those things made a big difference, and we're doing it week in, week out and it's the same people who are doing it unfortunately."
Russian Roman Seleznev has been found guilty in the US of running a hacking scheme that stole $169m (£131m).
[NEXT_CONCEPT]
Newcastle Falcons are yet to show their true potential after a "frustrating" winless start to the Premiership, says director of rugby Dean Richards.