The Phillies slugger was fanned on a 2-2 slider from Nationals right-hander Joel Hanrahan, equaling the mark established in 2004 by the Reds' Adam Dunn.
Howard, who has struck out 35 times in September, stormed to the mark in a hurry. The reigning National League Most Valuable Player fanned four times on Friday.
Ken Mandel is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.