His 19-year prison sentence was widely condemned by rights groups and in the West as punishment for daring to cross President Vladimir Putin.
Through messages passed through his lawyers, he posted regularly on social media in a characteristically optimistic and light-hearted tone.
Here is what Navalny’s final weeks looked like, in his own words:
‘Ho-ho-ho’
On December 26, Navalny posted his first message from his new Arctic prison colony, having disappeared for weeks after being moved from his former prison closer to Moscow.
The icy IK-3 prison colony in the Siberian region of Yamal-Nenets, some 2,000 kilometres (1,200 miles) from his native Moscow, would be where he spent his final few weeks.
“I am your new grandfather Frost,” Navalny said, in his usual tongue-in-cheek manner.
“I have a tulup, an ushanka and I will have valenki soon,” he said, referring to traditional furry Russian winter coats, hats and boots.
“I now live above the Arctic Circle … But I don’t say ‘ho-ho-ho, I say ‘oh-oh-oh’ when I look out the window, where first there is night, then evening, then night again.”
Navalny said he was tired from the 20-day journey from his previous prison in the central Vladimir region, close to Moscow.
“Don’t worry about me, everything is well. I am so happy that I finally got here.”
A few weeks later, after a spell in quarantine, Navalny shared more details about his conditions in the new Arctic prison.
“The idea that Putin was pleased (enough) that he had put me in a barracks in the Far North that they would stop throwing me in solitary confinement was … naive,” the 47-year-old said.
Prison authorities told him: “‘Convict Navalny refused to introduce himself in the correct way’. Seven days in solitary confinement.”
Navalny spent more than 300 days in solitary confinement — or a “punishment cell” as his colleagues called it, based on its name in Russian — during his three years in prison.
He was ordered there on 27 occasions, often for minor infringements of prison protocol.
Allowed out for a daily walk in the pitch black of at 6:30 a.m., Navalny said: “I promised myself I would go out in any weather.”
His cell was “11 steps from wall to wall”.
“It has never been colder than minus 32 (Celsius). Even in such a temperature you can walk more than half an hour — only if you have the time to grow back a nose, ears and fingers,” he said in a January 9 post.