Bolotnaya Ploshchad protester Alexei Gaskarov is to be released on Oct. 27 after serving his entire 3.5 year sentence, the Interfax news agency reported on Thursday.
Gaskarov's lawyer said he would leave the No. 6 correctional colony in the Tula region at 11 a.m.
Two appeals for early release had been rejected, the first in June 2015 and the second one a year later.
Gaskarov had been sentenced in August 2014 after being found guilty of taking part in mass disorder and using violence against police officials during the Bolotnaya Ploshchad protests of May 6, 2012. The protest, one of the largest in Russia since the 1990s, was one of a series of mass demonstrations that had started in December 2011 in response to allegedly fraudulent State Duma elections.
The May 6 protest took place the day before the inauguration of Vladimir Putin for his third term as president.