The court decision came a month after Taimour Subki was sent to jail for making the claim in a television interview.
A misdemeanour court had convicted him of spreading "false news that disturbs the public peace".
Subki, who runs a Facebook page titled "The Diary of a Crushed Husband", made the claim in a television interview in December, sparking an uproar.
A backlash on social media had already led to the cancellation of the talk show, aired on private satellite station CBC, which hosted Subki.
"Many women cheat on their husbands... I can say that 30 percent of women are ready to be deviant," Subki said, pointing to the southern cities of "Asyut, Minya, Sohag, Qena, Luxor and Aswan."
Subki said his remarks had been taken out of context.