Shtein, 27, was found guilty of spreading "war fakes" in connection with a March 2022 post on X, in which she accused Russian soldiers captured by Ukraine of "bombing foreign cities and killing people", Russian independent news outlet Mediazona reported.
At least 19,855 people have been detained in Russia for expressing anti-war views since President Vladimir Putin ordered a full-scale invasion of Ukraine on Feb. 24, 2022, according to OVD-Info, a group that monitors crackdowns on dissent.
Those found guilty of spreading "false information" about Russia's army risk 10 years in prison.
The Moscow court said Shtein, who served as a Moscow municipal deputy until 2022, would begin her sentence once she could be extradited to Russia.
Pussy Riot, a feminist opposition group, rose to prominence by donning balaclavas and storming into Moscow's Christ the Saviour Cathedral in Feb. 2012, shouting out a song against Putin. Many of its members have been jailed in Russia.
Just weeks after the invasion of Ukraine began, Shtein fled house arrest in Moscow with her girlfriend and fellow Pussy Riot member Maria Alyokhina.
The pair donned the ubiquitous lime-green uniforms of Moscow's food delivery couriers to evade police and snuck out of the city, eventually reaching Lithuania, Alyokhina told the New York Times.
They settled in Iceland, which granted them citizenship in May 2023, according to local media there.
Prosecutors had requested an eight-and-a-half year sentence for Shtein, who on Wednesday joked in a post on X that her mother had "bet" they would ask for nine years.
(Reporting and writing by Lucy Papachristou; Editing by Gareth Jones)
