Guerrero, 30, presented a locked gun box to a ticket agent during check-in that contained an unloaded .40-caliber handgun and three unloaded magazines, Queens District Attorney Richard Brown said. The gun was registered in California but was not legal to carry in New York, the district attorney's office said.
"I hope that Mr. Guerrero fights better than he thinks," Brown said in a statement. "For anyone who hasn't gotten the message, let me be crystal clear. You cannot bring an unlicensed weapon - loaded or unloaded - into this county or this city. And if you do, you will be arrested and face felony charges."
Representatives for Guerrero, of Gilroy, Calif., said in a statement that he was at the airport and "made sure to advise the authorities that they needed to be aware that he had a firearm, which was unloaded and in a locked safe box with his luggage to be checked."
"He was carrying no ammunition and was within his legal right to possess such firearm in the state in which he resides," according to the joint statement from Team Guerrero, Mayweather Promotions and Golden Boy Promotions.
Guerrero was arraigned on charges including criminal possession of a firearm. He was released on his own recognizance and ordered to appear in court May 14. If convicted, Guerrero faces up to four years in prison.
The joint statement said the current WBC welterweight champion was heading back to Las Vegas on Thursday to continue to train for a May 4 bout against Floyd Mayweather Jr.
Guerrero was in New York promoting the fight in radio and TV interviews. The bout airs on Showtime pay per view.
Showtime and the Nevada State Athletic Commission did not return calls seeking comment about whether Guerrero's arrest would affect the fight.