Before the promotion, Walters was hitting a combined .280 with 11 home runs and 43 RBIs for Class A Potomac and Double-A Harrisburg. He joined the Nationals' organization in July 2011, in a trade that sent right-hander Jason Marquis to the D-backs.
Washington has been looking for a backup middle infielder since shortstop Ian Desmond went down with an oblique injury last month. It's not known when Desmond will return to action.
If Walters were promoted to the big leagues, he would spell Danny Espinosa and Steve Lombardozzi at shortstop and second base, respectively.
Bill Ladson is a reporter for MLB.com and writes an MLBlog, All Nats All the time. He also could be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.