Prosecutors in Russia have said he violated the parole terms of a suspended sentence for an embezzlement conviction in 2014.
It comes just hours after Mr Navalny accused the Russian government of the "highest level of lawlessness" at his first hearing since his arrest.
The 44-year-old, who is one of Vladimir Putin's most prominent critics, blames Moscow for the attack which almost killed him, although the Kremlin denies any involvement.
He appeared at an ad-hoc hearing - held in a police station in Khimki, outside Moscow - on Monday afternoon.
In a video posted to social media by his spokeswoman Kira Yarmysh, Mr Navalny said: "I don't understand what's going on. A minute ago, I was brought from cell here to meet my lawyers."
He added: "I came here and here is the Khimki court session taking place. Some strangers are filming me on camera.
"Why the court session is taking place in police station I cannot understand. Why was no one was informed?"
"I have seen a lot of jokes about judicial system here… It's the highest level of lawlessness. I cannot call it any other word," he added.
Mr Navalny was arrested soon after his flight from Germany landed in Moscow on Sunday.
It was Mr Navalny's first time back in his home country after he was poisoned with the nerve agent Novichok and nearly died, in August.
Footage from the airport showed Mr Navalny kissing his wife goodbye as he was arrested and led away.
Mr Navalny's detention has drawn widespread condemnation from governments across the world, with the European Union, Germany and the US all speaking out about the arrest.
Foreign Secretary Dominic Raab has told Russia to immediately release Mr Navalny.
Mr Raab tweeted: "It is appalling that Alexey Navalny, the victim of a despicable crime, has been detained by Russian authorities. He must be immediately released.
"Rather than persecuting Mr Navalny, Russia should explain how a chemical weapon came to be used on Russian soil."
US secretary of state Mike Pompeo said he was “deeply troubled” by Mr Navalny’s arrest, while adding a veiled criticism of Russian president Vladimir Putin.
“Confident political leaders do not fear competing voices, nor see the need to commit violence against or wrongfully detain, political opponents,” he said.