World leaders are congratulating Vladimir Putin on his election for a new six-year term as Russian president, but Western leaders have been slow to respond amid recent tensions.
Chinese President Xi Jinping said his country's partnership with Russia was at its "best level in history".
Mr Putin got more than 76% of the vote, official results show.
He said he was considering changes to his government, including the post of prime minister.
Former President Dmitry Medvedev has held the post since he changed places in 2012 with Mr Putin, who has ruled the country as either president or prime minister since 1999.
The main opposition leader, Alexei Navalny, was barred from the race.
What has been the reaction around the world?
In a congratulatory message to Mr Putin, China's Mr Xi said: "Currently, the China-Russia comprehensive strategic cooperative partnership is at the best level in history, which sets an example for building a new type of international relations."
Japanese Prime Minister Shinzo Abe spoke to Mr Putin about working towards the denuclearisation of the Korean peninsula, the Japanese Foreign Ministry said.
The leaders of Iran, Kazakhstan, Belarus, Venezuela, Bolivia and Cuba were among others who sent their best wishes.
Steffen Seibert, spokesman for German Chancellor Angela Merkel, said she would send the Russian president a telegram "very soon".
"We have differences of opinion with Russia and we very clearly criticise Russia's policies on some issues - Ukraine, Syria," he said.
But observers from the Organisation for Security and Cooperation in Europe said in a report: "Restrictions on the fundamental freedoms of assembly, association and expression, as well as on candidate registration, have limited the space for political engagement and resulted in a lack of genuine competition."
However, the report added that the electoral commission had administered the election efficiently.
Tensions between Russia and the West have deepened in recent weeks after the poisoning of ex-spy Sergei Skripal and his daughter Yulia in Britain. The UK government blamed the nerve agent attack on Russia.
The UK expelled 23 Russian diplomats from London, prompting a tit-for-tat response from Moscow. The US, which has backed the UK's condemnation of Russia, recently imposed sanctions on a group of Russians over alleged interference in the 2016 election.
What happened in the election?
The scale of victory - which had been widely predicted - appears to be a marked increase in Mr Putin's share of the vote from 2012, when he won 64%. Turnout, at more than 67%, also appears to be up.
Addressing a rally in Moscow, Mr Putin said voters had "recognised the achievements of the last few years".
His nearest competitor, millionaire communist Pavel Grudinin, received slightly less than 12%.
The race also included Ksenia Sobchak, a former reality TV host, and veteran nationalist Vladimir Zhirinovsky - they got less than 2% and less than 6% respectively.
What criticisms have there been?
Video recordings from polling stations showed irregularities in a number of towns and cities across Russia. Several showed election officials stuffing boxes with ballot papers.
Mr Navalny was excluded from the election because of an embezzlement conviction that he said was manufactured by the Kremlin.
During polling day, independent election monitoring group Golos reported hundreds of irregularities.
They include webcams at polling stations obstructed by balloons and other obstacles, as this video from the Siberian city of Kemerovo posted by the group demonstrates:
But Ella Pamfilova, head of the Central Electoral Commission, said there were only half as many reported violations compared to 2012, and that none had been serious.
Sunday's vote was also the first in Crimea since Russia seized the region from Ukraine. Mr Putin's victory rally coincided with the anniversary of the annexation.
The annexation was bitterly contested by Kiev and ratcheted up tensions between Russia and the West. Russians living in Ukraine were unable to take part in Sunday's vote because access to Russian diplomatic missions was blocked by the Kiev government.
What next for Russia?
The BBC's Sarah Rainsford in Moscow says a sudden thaw with the West seems unlikely, given Mr Putin's first comments after his victory.
Western governments are expecting more cyber-attacks and attempts to disrupt elections, previous cases of which have been blamed on Russia.
But some analysts believe that squaring up to the West has only limited appeal, and sooner or later the Russian president will have to address domestic concerns like education, housing and health care.
The question also remains about whether Mr Putin will continue as president after this term ends.
According to the constitution he is required to step down in 2024, but he could change the rules to eliminate term limits.
However, he does not seem willing to carry on for too long, and laughed off a question from a journalist about standing in 2030.
European newspapers see Cold War climate
By BBC Monitoring
Germany's Bild tabloid asks "Has the poison thriller helped Putin?" and quotes Mr Putin's campaign spokesperson thanking Britain for "unjustly accusing Russia" and putting pressure on Moscow "at the right time" which led to a surge of Russian voters "gathering around the centre of power - and that is Putin".
French business daily Les Echos says Mr Putin was "re-elected in a Cold War climate". The paper adds: "Vladimir Putin has won the bet that was impossible to lose: to be re-elected amid a full-scale crisis with the West."
Poland's conservative Rzeczpospolita says Mr Putin's re-election means a "further policy of confrontation with the West". One expert tells the paper: "Russia has depleted its means of development, meaning that now Russia will only rely on force and expansion".