Navalny's allies have declared a moratorium on street rallies until the spring after police detained thousands of people at protests in the past few weeks against the opposition politician's arrest and imprisonment.
But they want Russians to show solidarity with Navalny by gathering outside their homes for 15 minutes on Valentine's Day evening, shining their mobile phone torches and arranging candles in the shape of a heart.
"(President Vladimir) Putin is fear. Navalny is love. That's why we will win," Leonid Volkov, one of Navalny's close allies, wrote on Twitter when calling on people to gather.
Navalny was arrested last month on his return from Germany following treatment for poisoning, in Siberia, with what many Western countries say was a nerve agent. He was jailed on February 2 for violating parole on what he said were trumped-up charges.
He blames Putin for the poisoning, and Western countries are considering new sanctions against Russia. The Kremlin denies any involvement and questions whether Navalny was poisoned.
Volkov, who is based in Lithuania, is one of several Navalny allies now abroad or under house arrest in Russia.
He urged people to flood social media with pictures of Sunday's gatherings - a new venture for the opposition that resembles political actions in neighboring Belarus - using the hashtag #loveisstrongerthanfear in Russian.
Another activist has called on women to form a human chain on a pedestrian street in Moscow on Sunday afternoon in support of Navalny's wife Yulia, who according to media reports flew to Germany this week, and other women affected by the police crackdown against protesters.
Russian law enforcement agencies said on Thursday that people taking part in unsanctioned rallies could face criminal charges.
Some rights groups accuse police of using disproportionate force against protesters in recent weeks. The Kremlin has denied repression by police and says the protests were illegal as they were not approved and risk spreading COVID-19.