Author of The New Iraq: Rebuilding the Country for Its People, Joseph Braude also admitted lying to customs officials at Kennedy International Airport on Wednesday.
Changing his plea on the second day of testimony in his trial at the Federal District Court in Brooklyn, New York, he confessed to bringing back three 4000-year-old marble and alabaster stone seals he knew to be stolen.
Hiding the ancient objects in his suitcase, Braude told Judge Allyne Ross he had even told customs officials he had never travelled to Iraq in an attempt to stop them searching his bags.
"I accept responsibility for my conduct, and I deeply regret my actions," he told the court.
Scheduled for 25 October, Judge Ross could sentence the academic to up to 16 months in prison or merely put him on probation.
The 29-year-old had originally denied the charges, despite advice from his lawyer Benjamin Brafman to avoid a trial.
Speaking to reporters outside the courtroom, Brafman said: "It's sometimes the case that a good person takes a very long time to accept that he has violated the law because of the way he has lived his whole life."
After his plea was changed, the United States attorney's office said: "Through his guilty plea Mr Braude admitted that he knew exactly what he was doing - smuggling precious antiquities looted from the Iraqi people."
A graduate of Yale and Princeton, Braude spent much of the past decade travelling throughout the Arab world and became fluent in Arabic, Farsi and Hebrew.
He worked at an Islamic archive in the United Arab Emirates, where he helped recover and preserve antique Arabic manuscripts. He has also been a federal consultant on "terrorist activities".