On Thursday, Putin signed a decree recognizing the independence of two Ukrainian regions and laying the groundwork for Russia's annexation.
Putin is expected to announce Russia's annexation of the two territories along with the rest of the country.
Before they can become part of Russia, the territories need to be declared independent of Ukraine.
The eastern Ukrainian regions will become part of Russia on Friday, according to the Kremlin.
The ceremony would discuss the accession of new territories into the Russian Federation.
The regions to be annexed make up 15% of the territory.
The four Russian-occupied regions held sham referendums. Ukrainian families were threatened with violence if they refused to participate in the polls, which were organized by the pro- Russian rebels.
The illegal polls were similar to Russia's illegal annexation of the peninsula. The election officials in the region announced an overwhelming vote in favor of unifying with Russia.
Russian troops currently control most of the Luhansk region and around two-thirds of the Donetsk region. The referendums may be part of Russia's plan to hold off a Ukrainian counteroffensive in Kherson.
Russia's actions have been slammed by the UN Secretary General.
"Any annexation of a State's territory by another State is a violation of the principles of the UN Charter and international law," he said.
One of the five permanent members of the Security Council is the Russian Federation. He said that any decision to annex the regions of Ukraine would be condemned.