Events are planned in Russia and more than 20 other countries on Monday, according to Navalny's team, which works in exile.
A dozen cities in Germany, including Berlin, Hamburg and Leipzig, are commemorating the harsh critic of Russian President Vladimir Putin. The dissident was tortured to death on February 16, 2024, in a penal camp in the Arctic region, they say.
People can lay flowers at the Borisovskoye Cemetery in Moscow, where Navalny's grave is located. Rallies are banned in Russia.
The politician's widow Yulia Navalnaya accuses Putin of murdering her husband.
On Saturday, Germany, Sweden, the Netherlands, France and the United Kingdom alleged that analyses of Navalny's remains showed traces of the highly potent toxin epibatidine.
"Russia claimed that Navalny died of natural causes. But given the toxicity of epibatidine and reported symptoms, poisoning was highly likely the cause of his death. Navalny died while held in prison, meaning Russia had the means, motive and opportunity to administer this poison to him," said a joint statement made on the sidelines of the Munich Security Conference.
It is unclear how Navalny's tissue samples ended up in the West.
Amnesty International has called for clarification of the circumstances surrounding his death.
In 2020, Navalny narrowly survived an assassination attempt with the chemical warfare agent Novichok.
The Russian authorities claim Navalny died of natural causes.
Despite requests from Navalny's mother, they did not release his body for days. This led to fears that any traces of poison might no longer be detectable.
Human rights activists have criticised the lack of clarification in Russia.
"To this day, the Russian authorities are covering up the circumstances of his death," said Julia Duchrow, Amnesty's secretary general in its German office.
At the same time, the power apparatus was waging a "merciless campaign" against Navalny's supporters, she said. His lawyers are in prison.
"This systematic repression shows how uncompromisingly the Russian state acts against any form of peaceful criticism," she said. Any criticism of the government is criminalised.
Duchrow appealed to the Russian authorities to release those detained and to overturn "unjustified convictions" while also calling on the German government to help politically persecuted people from Russia, for example through flexible visa and residence regulations.
Navalny was one of thousands of political prisoners in Russia, only a few of whom Putin has released in exchange for Russians imprisoned in the West.
Human rights activists believe that many prisoners are in mortal danger in Russian penal camps due to torture or other conditions criticised as inhumane.
The human rights organisation Memorial, which keeps a list of political prisoners, estimates Russia is holding at least 5027 people in prison for political reasons, calling the figure "a minimum estimate."
"We assume that in reality there could be at least twice as many prisoners," it said in a statement.
