Edelman, 25, was accused of grabbing the woman's crotch during a Halloween party at a Boston nightclub.
Prosecutors said Thursday they decided to drop the charge after reviewing video surveillance and witness statements and interviewing the woman several times.
They said video indicates Edelman had just "fleeting" contact with the woman and didn't commit a crime.
Edelman issued a statement through the Patriots saying he's appreciative of work by prosecutors and his attorney and humbled by the team's support. He said he's looking forward to focusing on football.
Edelman has played receiver and defensive back for the Patriots this season, and he has returned punts as well.
Copyright 2011 by The Associated Press