Over the course of the Russian invasion of Ukraine, which began in February 2022, irregular military units began to play a more prominent role in the fighting, alongside the regular Russian Armed Forces. In the face of waning recruitment levels for the military as casualties mounted, the Russian government increasingly turned to a variety of mercenaries, militias, paramilitaries, and mobilized convicts. In a similar fashion to the pro-Russian people's militias in Ukraine such as the DPR People's Militia and LPR People's Militia, the combat effectiveness of these irregular combatants varies greatly. This can be seen in the contrast between the poorly equipped and virtually untrained prisoners serving under Storm-Z and the professional mercenaries of PMC Wagner. The Wagner group itself also used convicts in its ranks, alongside its more experienced cadre of fighters. The organization garnered much notoriety as it took up an increasingly prominent role in the fighting in late 2022, culminating in the Battle of Bakhmut.

Russia's invasion effort has left the military strapped for volunteers to join the armed forces. In an attempt to circumvent this, Russia has employed a number of tactics to garner more recruits. The largest is to have Russian companies and organizations that are directly or indirectly tied to the Russian government to raise mercenary groups. The basis of these formations is that the higher pay and more stringent recruitment methods will garner more interest and volunteers from civilians, mainly veterans, who have not already joined the war effort. Similarly, many of Russia's subdivisions are paid by the government to raise volunteer militias, usually consisting of between 200 and 400 personnel. These units are largely former veterans, mostly of the Soviet–Afghan War and are between the ages of 50 and 60, however, that is not always the case, as the key driver for recruitment to these units is the higher pay they offer than a mobilized conscript, and the cult of personality around the politicians that created the units. In 2015 Russia created the Combat Army Reserves (BARS) in an attempt to create an analogous reservist organization to the British Territorial Army or the United States Army Reserve with members being paid a salary to undergo part time military training. Additionally, most of the members of BARS units are retained veterans from the War in Donbass.

Fakel, Plamya and Potok are voluntary military formations, founded in 2023 by the Russian state run gas monopoly Gazprom subsidiary Gazprom Neft, as a more loyal alternative for the Wagner Group, which at the time had just begun clashing with Russian high command on issues of supplies and tactics. Fakel and Plamya reportedly are directly subordinate to the Russian Ministry of Defence, while Potok joined Redut PMC, a PMC which is also controlled by the Russian MoD. Although the company has no official political affiliation, several members stated they are fighting to restore the Russian Empire. The company hires primarily from Gazprom employees, who are promised that their old jobs are guaranteed for them when they return, and a large portion of the fighters are Gazprom security guards.

The Alexander Nevsky private army is also affiliated with Gazprom.

The Tsar's Wolves (Russian: Царские волки) was formed in 2014 during the War in Donbas as a way to circumvent Russia sending assistance to Russian separatist forces. The group consists of "experienced military advisers and experts" that provided "military-technical support" to the separatist forces. On November 11, 2022, former Roscosmos director Dmitry Rogozin announced that he was the new leader of the group shortly after his ousting from the agency. The unit works closely with the Russian Military–industrial complex to develop and test new technology in a "baptism of fire in the Donbas." The group's self stated goal is to restore the glory, and the borders, of the Russian Empire. The group has seen front-line combat during the 2023 Ukrainian counteroffensive where they performed a failed defensive action against the Ukrainian 47th Mechanized Brigade over the village of Lobkove.

The Uran (Уран) battalion is a PMC owned and operated by the Russian space agency, Roscosmos, and received international attention on June 16, 2023, when the agency released a recruitment video for the group styled like a trailer to a First-person shooter. The unit is named after the planet Uranus and has put an emphasis on their loyalty to the Russian state in an attempt to sway Wagner group fighters to join them after the Wagner Group rebellion. Mercenaries in the battalion receive a signing bonus of $1,200 and a monthly salary of $3,000. The group has ties to a Moscow based MMA club, and the Shield and Sword patriotic and veteran organization.^{[citation needed]} The unit has yet to see front-line combat in the war, and its existence, and Roscomos' active recruitment for the group, has strained international space cooperation, namely with NASA and the policy of Russian membership in the International Space Station. The group has put an emphasis on recruiting from the 170,000 employees of Roscosmos, with their recruitment videos playing throughout Roscosmos installations.

Redut PMC is a Russian Private Military and Security Company (PMSC) that is part of the "Antiterror-family"—which consists of similarly named PMSCs that protect commercial operations of Russian companies. It is deployed in the Russian invasion and was deployed in the Balkans, Africa, Middle East, Southeast Asia and the Caribbean.

Created as a more "specialized" alternative to Wagner, Patriot has modeled itself after the American Blackwater PMC by hiring only young ex-military paid $2,500. Founded and led by former Colonel General Leonid Ivashov who also leads the Honor and Motherland patriotic organization and is a chairman of the All-Russian Officers' Assembly. The unit has seen combat around Vuhledar, but have also been sent to Sudan, Gabon, and the Central African Republic.