Yevgeny Prigozhin, 62, released a series of messages from late Friday into Saturday, claiming that he and his mercenary troops had entered the southern Russian city of Rostov-on-Don and taken control of its military sites.
Here is what we know so far:
What sparked the rebellion?
For months, Prigozhin has been locked in a power struggle with the military top brass, blaming them for his troops' deaths in eastern Ukraine.
He has repeatedly accused them of failing to equip his private army adequately, of holding up progress with bureaucracy, while claiming victories won by Wagner as their own.
On Friday, Prigozhin's anger appeared to boil over, as he accused Moscow's military leadership of ordering strikes on Wagner's camps and killing a large number of forces.
He said they had to be stopped and vowed to "go to the end."
He later claimed his forces had downed a Russian military helicopter.
Hours later, the leader of the mercenary group said he had military sites in southern Russia's Rostov-on-Don "under control."
How is Moscow reacting?
The Kremlin had said overnight that "measures are being taken" against the mutiny. Russia has tightened security in Moscow and several regions such as Rostov and Lipetsk.
Putin has called the Wagner mutiny a "deadly threat" to Russia and urged the country to unite.
Branding the action by Wagner mercenaries as "treason", he vowed "inevitable punishment."
Who are the Wagner troops?
The private army had been involved in conflicts in the Middle East and Africa but always denied involvement.
Prigozhin last year admitted he had founded the group, recruiting the soldiers from Russian prisons in exchange for amnesty.
In eastern Ukraine, the mercenary unit has been spearheading Russia's costly battles. It had been at the forefront of the months-long assault for Bakhmut, capturing the site for Russia, but at huge losses.
How this affects Russia's war
The rebellion marks the most serious challenge yet to Putin's long rule and Russia's most serious security crisis since he came to power in late 1999.
It would divert attention and resources away from the battlefields in Ukraine, at a time when Kyiv is in the midst of a counteroffensive to seize back territory.
Ukraine's army has said it was "watching" the infighting between Prigozhin and Putin.
Moscow meanwhile has warned that Kyiv's army was seizing the moment to concentrate its troops "for offensive actions" near Bakhmut.
The significance of the mutiny was also not lost on world leaders, with leaders of the United States, France and Germany all saying that they are watching developments closely.