Abdeen Misdemeanor Court said that the 77 men were convicted of committing acts of violence and riots at downtown's Ramses Square last August after security forces dispersed pro-Morsi sit-ins, Xinhua reported citing local media.
Meanwhile, another court renewed detention of 444 pro-Morsi defendants for 45 days over similar charges.
Morsi was ousted by the military last July after mass protests against his one-year rule, followed by a massive security crackdown on his supporters.
In mid-August, security forces disbanded two major pro-Morsi sit-ins in Cairo and Giza, which left about 1,000 killed and thousands arrested.
Since his removal, Morsi's supporters, led by the Muslim Brotherhood and Islamist affiliates, have been holding constant anti-government protests in defiance of a new anti-protest law.
The Brotherhood has been blacklisted as "a terrorist organization" by the government in late December.