Dukes, who was released by the Nationals during Spring Training, signed with the Newark Bears of the Atlantic League, the team announced on its Web site Thursday.
Dukes, 26, teams up with other ex-big leaguers in Daryle Ward, Brian Barton and Carl Everett.
A third-round Draft pick by the Rays in 2002, Dukes came to the Nationals with a troubled past and several bouts of immaturity, but he never got into any legal trouble in Washington. He hit .250 with eight homers in 107 games for Washington in 2009. Dukes started off Grapefruit League play this spring 3-for-20 with five strikeouts and, in a surprising move, the Nats released him on March 17.
At the time, Rizzo said the move was purely a baseball decision, but added that the clubhouse would be more united.
Alden Gonzalez is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.