The reunification treaty was ratified by both houses of Russia's Parliament. The Duma, the lower chamber, approved the treaty Thursday and the Federation Council, the upper chamber, approved it Friday, RIA Novosti reported.
Crimea and the city of Sevastopol, which has special status within the region, were added as subjects of the Russian Federation after voters Sunday overwhelmingly approved a referendum to secede from Ukraine and rejoin Russia. Under terms of the decree, the Russian Federation will have 85 regions, up from 83.
Putin, Crimean Prime Minister Sergei Aksyonov and other regional leaders signed an agreement Tuesday in Moscow stating that Crimea was to be considered Russian territory.
Crimea was part of Russia until it was given to Ukraine by former Soviet Union leaders in 1954.
Leaders in pro-Russia Crimea and Moscow refused to recognize the legitimacy of the new government in Kiev that came to power after months of bloody protests that eventually led to the ouster of pro-Russia President Viktor Yanukovych. He surfaced in Russia several days after he was chased from office.
During a meeting of Russia's Security Council Friday, Putin said the Kremlin wouldn't impose retaliatory sanctions against the United States or introduce visa rules concerning Ukraine, ITAR-Tass reported.
Foreign Affairs Minister Sergei Lavrov said the government in Kiev was making controversial statements concerning relations with Russia.
"In particular, there were statements made about either their withdrawal or suspension of participation in the Commonwealth of Independent States and intention to introduce [a] visa regime with Russia. In this situation, if it comes to this, we would also inform you about our proposals," Lavrov said.
"As concerns the first case -- the U.S. sanctions, and the second case, Ukraine's introduction of visa regulations -- I think we should still refrain from retaliatory moves," Russia's top diplomat said.
"First of all, I'll speak of visa rules with Ukraine. If we introduce visa regulations, millions of innocent Ukrainians, who are not wealthy even without this, work in Russia and earn not a big money to support their families, will suffer.
Putin said he was concerned that if Russia imposed visa restrictions on Ukrainians, millions of innocent Ukrainians may be impacted
"We don't need to do this," Putin said.