O'Reilly is the conservative host of "The O'Reilly Factor," while Stewart is the liberal star of "The Daily Show."
The debate, billed as "The Rumble in the Air-Conditioned Auditorium" took place Saturday at George Washington University before an audience of 1,500 people and thousands of people streaming online from home, The New York Times reported Sunday.
The two rarely agreed on any topic, particularly on entitlements, which O'Reilly said made it easier for people to take advantage of the system. Stewart pointed out that O'Reilly's family benefited from government help when he was a child.
"Why is it that if you take advantage of a tax break and you're a corporation, you're a smart businessman, but if you take advantage of something that you need to not be hungry, you're a loser?" Stewart said.
When moderator E.D. Hill, of CNN, asked if either man had learned anything during the debate, O'Reilly said, "Now I know I'm right."