Alyokhina is among the several opposition figures accused of calling for protests in January when Navalny was arrested on his return to Russia from Germany after surviving a nerve agent poisoning attack.
The press service of Moscow's Preobrazhensky district court said on Telegram that Alyokhina was "found guilty" and sentenced to "one year of restricted movement".
It said Alyokhina will be banned from leaving her home between 10 pm and 6 am as well as from attending mass events and leaving Moscow.
A veteran member of the Pussy Riot feminist group, Alyokhina spent two years in prison for taking part in the group's 2012 protest performance in neon balaclavas inside Moscow's Christ the Saviour Cathedral.
Kremlin critics say Russia's opposition is facing unprecedented pressure ahead of a parliamentary vote later this month, with Navalny in jail on charges he says are politically motivated.
In June, Russia labelled Navalny's key organisations as extremist, banning them in the country and barring his rallies for running in the polls.
Several other opposition figures, including Alyokhina's partner and Pussy Riot member Lusya Shtein, were sentenced in the so-called "sanitary case" for breaching coronavirus regulations at the rallies.
The case also targeted Navalny aides Lyubov Sobol and Kira Yarmysh, who were sentenced to restricted movement, and Navalny's brother Oleg, who received a one-year suspended sentence.
Several Navalny allies have fled Russia under pressure from authorities.
