Nelson Chatman 31, smiled as the jury foreman rendered the not guilty verdict after just 75 minutes of deliberations, the New York Post reported.
Kennedy, 55, nodded her head and responded "yes" when the clerk asked each juror individually, "Is that your verdict?"
Mark Jankowitz, Chatman's court-appointed lawyer, said he took a chance on allowing Kennedy to be the jury since she has close ties to Manhattan District Attorney Cyrus Vance.
Chatman has served at least six years in prison on drug sale and attempted robbery convictions.
Kennedy declined to talk to reporters when she left the courthouse.