Prigozhin was said to be a passenger on an airplane that crashed on Wednesday in the Tver region, northwest of the Russian capital. He was believed to be traveling to Saint Petersburg along with other senior Wagner officials.
Putin expressed his condolences, calling Prigozhin a "talented man," but saying nothing to dispel rumors that his administration was behind the deadly crash.
From chef to mercenary chief
Prigozhin was born in what is now Saint Petersburg in 1961, and entered the food business. He met Putin in 1996 when he visited one of his restaurants. Prigozhin's catering company began to provide meals to the Kremlin, which made some dub him "Putin's chef."
The Wagner group was founded in 2014, when its fighters joined conflicts in eastern Ukraine. Its forces have also been working for Russia's interests in Syria and countries in Africa.
When Russia launched its military invasion of Ukraine, a large number of Wagner troops were believed to have been sent to the eastern city of Bakhmut, the scene of fierce fighting.
Prigozhin played a leading role in the war in Ukraine, but he criticized Russian Defense Minister Sergei Shoigu and others by name for not supplying enough ammunition to his group's front-line fighters. The confrontation culminated in June, when Prigozhin led his troops in a mutiny against Russian military leaders.
Putin said on Thursday that Prigozhin was "a man with a complicated fate, and he made serious mistakes in life. But he also achieved the results he needed, both for himself and, when I asked him, for the common cause."
Cause of plane crash unknown
Ukrainian President Volodymyr Zelenskyy denied that his country had played any role in the crash. He added, "I think everyone understands who has something to do with it."
Some Russian independent media speculated the plane was shot down with some type of surface-to-air missile. But the US Department of Defense said on Thursday that Pentagon experts dismissed that theory.
Analysts at the Washington-based Institute for the Study of War said the Kremlin had been weakening Prigozhin's authority since the mutiny. They called his death an "assassination" and said it was the "final step to eliminate" the Wagner group.