Santos, 34, was elected to represent New York’s 3rd Congressional District, beating Democrat Robert Zimmerman last month.
Representatives for Citigroup and Goldman Sachs told NBC New York they had no record of his employment.
In a statement Monday, Santos’ lawyer, Joseph Murray, dismissed the story, insisting that Santos was being smeared by "enemies" at the paper, and suggesting that Santos, posed a threat to Democrats.
"It is no surprise that Congressman-elect Santos has enemies at the New York Times who are attempting to smear his good name with these defamatory allegations.
The upset means Santos will succeed Democrat Tom Suozzi, who lost a primary bid for governor this year.