"This has now been resolved, and there is an affirmative response from the United States government... the extradition will proceed," Lopez Obrador told a regular news conference.
Cesar Duarte, who governed the northern border state of Chihuahua from 2010 to 2016, has been accused by Mexican authorities of misappropriating public funds.
His whereabouts are currently unknown.
Duarte, who governed Chihuahua for the long-ruling Institutional Revolutionary Party (PRI), has previously denied wrongdoing. His successor as governor, Javier Corral, has said that he believed Duarte fled to neighboring Texas.
Lopez Obrador, a leftist who took office about a year ago pledging to stamp out corruption, said Mexico's last attorney general did not properly submit the extradition request.