Alexei Navalny will be buried at a cemetery in Moscow on Friday, a spokesperson has confirmed.
The service will be held at Borisovskoye Cemetery, after a farewell ceremony at a Moscow church.
In a speech on Wednesday, the opposition leader’s widow Yulia said she didn’t know if the funeral would be peaceful or if police would arrest those who came to say goodbye.
Alexei Navalny died suddenly in an Arctic prison earlier this month.
For years, he was the most high-profile critic of Vladimir Putin. His widow has blamed the Russian president for his death, as have many world leaders.
Few details have been released on the cause of his death, and Russian authorities initially refused to hand Navalny’s body over to his mother Lyudmila. They finally relented eight days after he died.
On Tuesday, Navalny’s spokeswoman Kira Yarmish said his team were struggling to find somewhere to hold the ceremony – some funeral homes had claimed they were fully booked, she said, while others had refused when they found out who the event was for.
Details of the funeral came as Ms Navalnaya addressed the European Parliament in Strasbourg.
In it, she condemned Russia’s “brutal and sneaky” war in Ukraine, and said the West’s strategy for taking on Russia has not worked.
Instead, she urged MEPs to take inspiration from her late husband, calling him “an inventor” who “always had new ideas for everything, but especially for politics”.
Navalny’s team had originally wanted to hold the funeral on 29 February, but “it quickly became clear that there was not a single person around who could dig a grave on that day”, Ivan Zhdanov, the director of Alexei Navalny’s Anti-Corruption Foundation, wrote on X.
He implied that the reason for this was because Mr Putin is due to make a major speech on the same day.
He also encouraged people to arrive early “to have a chance to say goodbye to Alexei”.
A farewell ceremony will take place in the morning, followed by the funeral service at 14:00 (11:00 GMT) and the burial at 16:00 (13:00 GMT).
Since Navalny’s death at a notorious penal colony in the Arctic Circle on 16 February, some 400 people have been arrested across Russia after laying flowers for him, according to human rights group, OVO-Info.
His funeral on Friday is likely to be subject to a heavy police presence.
Earlier this week, an ally of Navalny alleged he was about to be freed in a prisoner swap when he died – but that President Putin changed his mind at the last moment.
The Kremlin has said it was unaware of such a deal.