A Cairo criminal court ordered on Sunday the release of Amr Ali, the coordinator of the April 6 Youth Movement, under precautionary measures pending investigations into charges of incitement against the state.
The prosecution had accused Ali of joining an illegal group, calling for protests, and inciting against the state.
The prosecution has the right to appeal the court order within 24 hours.
Amr Ali was arrested in September 2015 on charges of conspiring against the government.
A Cairo misdemeanor court sentenced Ali in February 2016 to three years in prison and fined him EGP 500 for conspiring against the state, obstructing the work of state institutions and joining an illegal organization.
In July 2016, an appeals court reduced that sentence to two years.
Ali was elected as the April 6 Youth Movement coordinator in October 2013, succeeding its founder and long-time coordinator Ahmed Maher.
The April 6 Youth Movement was founded in 2008 to support protesting workers and developed into one of the leading opposition groups during the last days of the Mubarak era.
In April 2014, the movement was banned by an Egyptian urgent matters court in a case of defaming the state.