Yevgeniy Prigozhin can be seen addressing a large group of detainees in footage shared on Twitter.
English subtitles appear to show Mr Prigozhin telling the inmates, who stood in a circle around him, that he represents a private military company.
Mr Prigozhin told prisoners their sentences would be thrown out in exchange for service with his group for six months.
“While you’re with us for a half a year, you’re always in the combat zone,” he told the group.
“No one falls back. No one retreats. No one surrenders into capture,” the subtitles said.
“During training you’ll be told about two grenades you must have with you when surrending,” he said.
English subtitles for the video of #Russia|n oligarch Prigozhin, who is close to Putin & runs the Wagner private military company, pitching to prison inmates, while trying to recruit them for his PMC to deploy in the #war against #Ukraine:
Via @kozako01 pic.twitter.com/TwCQ0Ok4yz
— Alex Kokcharov (@AlexKokcharov) September 14, 2022
The minimum age the Wagner group is recruiting is 22 years old, he said, and the maximum age is 50, depending on prisoners’ physicality.
Mr Prigozhin also warned the prisoners against drugs, alcohol and sex with “local women, flora, fauna, men....anyone” on the frontlines.
Anyone interested would have to undergo a phsyical test and possibly a lie detector test, he warned.
Speaking in what appeared to be a prison exercise yard, the mercenary boss also alluded to the difficulties Russia has faced in invasion, saying “this is a hard war, not even close to the likes of Chechnya and the others”.
It is unclear who filmed the video, when it occurred or how it was released.
Greater reliance on paid fighters from the Russian private military company Wagner Group for frontline duties rather than their usual work in special operations was seen as a further sign that Russia’s military is under stress six months into the war.
“This is a significant change from the previous employment of the group since 2015, when it typically undertook missions distinct from overt, large-scale regular Russian military activity,” the Ministry of Defence said in an intelligence update on July 30.
“Wagner’s role has probably changed because the Russian MoD has a major shortage of combat infantry however Wagner forces are highly unlikely to be sufficient to make a significant difference in the trajectory of the war.”
Meanwhile in August it was reported that Ukrainian missiles are reported to have hit a base belonging to pro-Russian Wagner Group mercenaries in the east of the country.
One Ukrainian politician said long-range HIMARS rockets were used in the attack on the city of Popasna.