But, Arenas has reached a plea agreement that would result in little or no jail time, several sources close to the case told The Washington Post. The newspaper had reported if convicted, Arenas could face a maximum five years in jail and a fine.
Arenas is expected to plead guilty Friday afternoon before D.C. Superior Court Judge Robert E. Morin, the Post reported. His court appearance is scheduled for 2:30 p.m. ET.
Arenas, who last week was suspended indefinitely without pay by NBA commissioner David Stern, was charged with carrying a pistol without a license outside a home or business.
The charges were filed in D.C. Superior Court in an "information," a document that generally signals a plea deal. The charge came directly from prosecutors and not in the form of an indictment.
"We are aware of the charge filed against Gilbert Arenas today and will continue to follow the ongoing legal process very carefully," the Wizards said in a statement issued Thursday. "We will also continue to cooperate fully with the proper authorities and the NBA."
Arenas' lawyer had no immediate comment. The NBA also declined to comment.
Arenas, a three-time All-Star, had admitted to taking unloaded guns out of his locker in a "misguided effort to play a joke" on a teammate following a gambling dispute during a team flight.
Arenas has said he kept multiple guns in his locker at the Verizon Center. He claims he wanted to keep them away from his children and didn't know it was illegal.
At least seven Wizards players and coach Flip Saunders have appeared before a grand jury or been questioned by authorities regarding the matter.
The teammate involved in the spat, Javaris Crittenton, had authorities search his apartment for a semiautomatic handgun in connection with the incident on Thursday afternoon but no evidence was seized.
The outcome of the legal process will have profound implications for Arenas' future in the NBA and with the Wizards specifically. Possession of a gun at an NBA arena is a violation of the league's collective bargaining agreement. Stern was particularly upset that Arenas joked about the matter and said that Arenas' conduct will "ultimately result in a substantial suspension, and perhaps worse."
The Wizards could also attempt to invoke the morals clause found in standard NBA contracts and void the remainder of the six-year, $111 million deal Arenas signed in summer 2008. The players' union would almost certainly contest such a move.
"We will continue to lend our full support to Gilbert and will assist him in every way possible to see this matter through," union executive director Billy Hunter said.
Arenas has played in only 34 games since signing the contract because of a knee injury and the guns-related suspension. He was averaging 22.6 points and 7.2 assists this season for the Wizards, who are 12-25 and in last place in the NBA's Southeast Division.
Information from The Associated Press was used in this report