The Sixers could have waited until Wednesday -- the final day -- to guarantee the remainder of his prorated one-year contract worth $1.3 million. Iverson was signed by the Sixers as a free agent on Dec. 3.
Philadelphia is 4-5 with Iverson in the lineup. The 34-year-old also sat out four games with arthritis in his left knee.
Iverson is averaging 15.7 points and 4.7 assists in 33 minutes a game.
"Since his arrival, Allen has done everything asked of him and has been an excellent teammate," Sixers general manager Ed Stefanski said in a statement before the Sixers faced the Washington Wizards on Tuesday night.