As Britain, Europe and the United States delivered a muted response to his victory, the Russian energy giant, Gazprom, flexed its muscles with neighbouring Ukraine by cutting gas supplies by more than a third in a dispute over what it alleges are unpaid bills and Ukraine's refusal to sign new contracts.
While hundreds of pro-Kremlin youths marched across the Moscow river to the US Embassy, wearing smocks with the slogans, "Russia forward" and "We will stand beside our country", more than 300 riot police swooped on protesters taking part in an unauthorised rally against the election results.
With 99.45 per cent of the votes counted, Mr Medvedev was on 70.23 per cent, Russia's central election commission (CEC) said. Because of a higher turnout, more Russians chose him than picked his mentor Vladimir Putin in the 2004 election – 52 million votes to 49.6 million.
Andreas Gross, the head of the only western group monitoring the vote, said the outcome might have reflected the wishes of the people, but there "was not freedom in these elections". However, the CEC dismissed Mr Gross's criticism. Referring to calls for greater transparency, Vladimir Churov, its head, said: "What should I do? Should I make CEC members work naked?"
In London, Gordon Brown, the Prime Minister, congratulated Mr Medvedev on his victory and sidestepped any questions about the vote.
"We have always said that we will look for opportunities to improve our relationship with Russia, and hope to see greater co-operation on an number of issues, but we should judge the new Russian government on its actions and the results of those actions," he said.
Britain's ties with Russia were badly strained over the Kremlin's refusal to send prime suspect Andrei Lugovoi to stand trial in London for the 2006 radiation poisoning death of former Russian security officer Alexander Litvinenko. It led to tit-for-tat expulsions of diplomats, and the closure of British Council offices in Russia after harassment by officials.
Mr Brown had written to Mr Medvedev to emphasise his hopes that London and Moscow could repair their relations, his spokesman said. He did not invite the new Russian president for talks at Downing Street, but said he was looking forward to meeting him at the G8 summit in July.
The White House said it was ready to "work with" Mr Medvedev, but one notable exception to the low-key reaction was Hillary Clinton, campaigning to be the future US president. She said the Russian election "marks a milestone in that country's retreat from democracy".
Mr Medvedev, 42, will be the youngest Russian leader since Tsar Nicholas II when he is sworn in on 7 May. He has asked Mr Putin, prevented by term limits from running for re-election, to be prime minister.
The new leader said his presidency would be a "direct continuation" of Mr Putin's eight years in office.
Both men say they will abide by the constitution, which gives the president control of foreign policy and "power ministries" such as defence and the security services, while the prime minister has the economy and social services.
But analysts question if their power-sharing arrangement can last in a nation accustomed to a single, strong leader.
GAS SUPPLIES CUT IN NEW ENERGY ROW
RUSSIA has had a series of bitter disputes with countries through which it ships gas, power and coal to Europe. Moscow has branded the energy transit states as parasites that have benefited from shipping fees and cheap Russian energy.
After cutting gas supplies to Ukraine by 25 per cent yesterday, Gazprom cut them a further 10 per cent, said a spokesman for Naftogaz, Ukraine's state oil and gas body.
Russia last cut gas supplies to Ukraine in 2006 in a dispute over payments and contracts, disrupting Europe's gas supplies. Gazprom and Ukraine yesterday said European supplies would be guaranteed.