The jury returned the verdict Friday.
Cox was accused of sexually assaulting a woman in September 2010 after a night of partying. The alleged victim became pregnant, and prosecutors said DNA tests indicated Cox was the father.
The woman testified that she believed she was drugged because she remembers little about what happened.
Cox denied having sex with the woman. His lawyer disputed the DNA test results and suggested they may have been contaminated.
Cox was charged with two counts of sexual assault. He could have faced two years to life in prison.