The move will be finalised with a Kremlin signing ceremony to add four Ukrainian regions to Russia.
It comes after a string of referendums in Ukraine, widely rejected by Western powers as being a "sham".
Moscow-backed proxy governments in Luhansk, Donetsk, Zaporizhzhia and Kherson held the votes this week.
Kremlin spokesman Dmitry Peskov said the ceremony would take place at 12pm on Friday "on agreements on the accession of new territories into the Russian Federation".
Russian President Vladimir Putin
Reuters
Ukraine's Volodymyr Zelenskyy has rejected the 'sham' referendums
UMIT BEKTAS
Agreements will be signed "with all four territories that held referendums and made corresponding requests to the Russian side," Peskov said.
Ukraine and the West have rejected the hastily arranged votes, held seven months after Russia's invasion.
Putin's decision to incorporate the regions into Russia means Moscow will annex vast areas across eastern and southern Ukraine.
The areas represent around 15 percent of Ukraine's total territory.
Following the signing ceremonies in the Kremlin, Putin will give a major speech and will meet with Moscow-appointed administrators of the Ukrainian regions.
It comes as new Russian military recruits are being urged to bring tampons, belonging to their wives and girlfriends, to the battlefield in order to use them as a bandage in the event they get shot, as military supplies deplete.
In a video circulating on social media, a woman who has been identified as a military doctor is seen giving what appears to be an introductory speech to new recruits.
The individual is seen telling them that supplies are woefully short and they will only be able to claim uniform.
Outlining all the things that an army would normally provide but are unable to due to the circumstances, the officer tells recruits to bring their own first aid, or the closest thing possible.
The officer can be heard saying in the clip: “Get your wives and girlfriends to get sanitary pads. The cheapest pads plus the cheapest tampons. You all know what the tampons are for?”
“To stop the bleeding?” One man is seen asking.
The woman responds: “You shove it right into the bullet wound and the tampon expands and applies pressure to the wounds."
In what appears to be a reference to a reference to Russia's wars in the country in 1994 and 2000, she said: "I know all that from Chechnya."