One of Egypt’s most renowned political activists and bloggers, Alaa Abd El Fattah, was released from prison early Friday after serving five years for taking part in an unauthorized protest of military trials for civilians and related charges.

Mr. Abd El Fattah became one of the best-known figures of Egypt’s 2011 uprising and a vocal critic of President Abdel Fattah el-Sisi’s use of military trials for civilians to crack down on dissent. He was arrested in 2014 for taking part in a demonstration months earlier against those trials, and sentenced in 2015 to five years in prison for protesting without a permit, rioting and assaulting public servants.

The military trials for civilians have continued broadly, allowed by the terms of Egypt’s 2014 Constitution.

Mr. Abd El Fattah’s lawyer, Taher Aboul Nasr, said that the procedures for the activist’s release were concluded on Wednesday. In front of the Qasr Al-Nil police station in central Cairo, Mr. Abd El Fattah’s family and friends were waiting for him to set foot outside.