In fact, the Florida Republican said, the card in question was a charge card -- not a credit card at all.
The freshman senator has enjoyed climbing poll numbers at the early state as well as national level, buoyed by a positively reviewed debate performance, but with his rise, has come increased scrutiny.
Speaking with ABC's "Good Morning America" on Wednesday, Rubio answered questions about his financial history brought up by his opponents and media investigations.
He refuted GOP front-runner Donald Trump's
attacks that he has a poor personal financial record and responded to a Tampa Bay Times story
that found he charged personal expenses to a Republican Party of Florida card.
"It wasn't a credit card, it was an American Express charge card secured under my personal credit in conjunction with the party," Rubio said.
The primary difference between a charge card and a credit card is that charge cards must be paid off each month, while credit cards allow a balance to be rolled over.
He also rejected Trump's recent onslaught of comments, including on Wednesday saying Rubio's finances are a "disaster" in New Hampshire.
"I only have one debt in the world, which is my mortgage on the home that me and my family live in in Miami," Rubio said, adding, "I obviously don't come from a wealthy family."
Trump has repeatedly cited Rubio's use of credit cards in his attack on Rubio, who's gained some traction on him in recent polls.
"When you check his credit cards take a look at what he has done with the Republican Party when he had access, what he had to put back in, and whether or not something should have happened," Trump said in New Hampshire. "You'll understand it. Marco Rubio has a basic disaster on finance."
Rubio said bills were sent to his home and he determined what was personal and what wasn't.
"If there was a personal expense, I paid it. If it was a party expense, the party paid it," Rubio said. "Now, I recognize in hindsight, I would do it different to avoid all this confusion. But the Republican Party never paid a single expense of mine -- personal expense."
According to the Tampa Bay Times story, Rubio has failed to release information about two years of using the card, and two years of records that were analyzed by the Times during his Senate campaign found that he "routinely" charged personal expenses on the card, sending about $16,000 to American Express to cover charges.
Rubio said Wednesday his campaign will release records "soon."
He called the story "not accurate" and said all the records are out there, even if they're not under his name.
"Every expense on that card is detailed in the Republican Party accounts that they file every month," Rubio said. "It doesn't say who they belong to, but every expense is on there, and as we've said, we'll release those soon."