Yevgeny Prigozhin, the late head of Wagner, who was murdered in a plane crash in August, had a previous aide named Andrei Troshev.
Two months after Wagner's army briefly invaded Moscow, he passed away.
According to the Kremlin, President Putin instructed Mr. Troshev to supervise volunteer combat units in Ukraine.
The president mentioned Ukraine when he stated Mr. Troshev may "volunteer units that can perform various combat tasks, especially, of course, in the zone of a special military operation."
Mr. Putin continued, "You are aware of the matters that need to be settled beforehand so that the combat effort proceeds in the best and most effective manner.
According to Dmitry Peskov, a spokesman for the Kremlin, Mr. Troshev "now works in the defense ministry."
Following Wagner's mutiny in June, Mr. Putin is making an effort to assert his control once more.
In less than a day, Prigozhin organized an uprising and dispatched troops to the southern city of Rostov, then further north toward Moscow, before fleeing. The largest challenge to Mr. Putin's leadership in 20 years came from this.
Last month, the president urged all Wagner employees and other Russian private military contractors to swear fealty to the Russian government.
Sedoi, Mr. Troshev's moniker, is Russian for "the one with grey hair" and is used to refer to him. He served in Russia's conflicts in Afghanistan and Chechnya, and he is a well-respected veteran.
Due to his work as the Wagner commander helping government forces in Syria in 2015 and 2016, he received the Hero of Russia Award.
On August 23, Prigozhin and nine other people perished in a collision close to Moscow.
After the attempted revolt, the Wagner leader was referred as by many as a "dead man walking."
Any involvement has been refuted by the Kremlin.