Medvedev, 46, was confirmed as the country's new Prime Minister with a vote of 299-144 in the State Duma.
Putin submitted Medvedev's candidacy for the post shortly after his inauguration as president yesterday. Medvedev occupied the presidential post in 2008-2012.
Before the vote, Putin, 59, who was sworn-in for a record third term as President, introduced Medvedev to the lawmakers as an experienced politician who stood behind crucial reforms in the country.
"In an open dialogue with civil society, he began serious reforms, reformed aimed to improve productivity of the government apparatus, the law-enforcement and judicial system that could protect people and defend truth and justice," Putin said.
"Today I am introducing the candidacy of Dmitry Medvedev for confirmation of his nomination for the position of Chairman of Government of the Russian Federation. I made this decision long ago," Putin said.
He pointed out that this decision was formulated "before society" in advance.
"We did not set forth, before the parliament or the general public, anything that could be described as a put-up job or some game of politics," the President emphasised.
Meanwhile, Russian police broke up a demonstration by hundreds of opposition activists who had spent the night outside the presidential administration offices to protest Putin's return as president.
Two prominent opposition leaders who had called their supporters to the small square in central Moscow were detained by police this morning but later released.
About 300 people were detained yesterday, police said, adding that they were later let off.
