Alexei Navalny, a key critic of Putin who has been barred from running in the election, claims people are being bussed to polling stations in a bid to improve turnout.
Exit polls are not final, and official results are gradually being released.
Exit polls showed Putin receiving almost 74 percent of votes that secured him another 6 years as Russia's leading man in charge.
He is calling for a boycott of the election, saying it is an undemocratic farce, and deploying supporters to collect evidence of anyone rigging the ballot to inflate turnout and support for Putin.
"We are a great big team together and I am a member of your team", he said, after a colorful show of high-energy musical performances.
During the campaign, Putin travelled across Russian Federation pledging to raise wages, spend more on the country's crumbling health care and education and modernize Russia's dilapidated infrastructure.
Putin's opponents alleged officials were trying to inflate the turnout, by opening up stalls selling discounted goods at polling stations, and instructing state employees to report back to their bosses that they had voted.
Many Russians say they would vote for Putin simply because they do not see an alternative, given his chokehold on domestic politics.
Russia's election monitors reported irregularities at voting stations across country, even though authorities were under orders to ensure that the voting was free and fair after violations marred Putin's last election in 2012.
Russians eligible to vote in the presidential elections have headed to cast their ballots, as polls first opened in the Far East regions of Kamchatka and Chukotka.
Vladimir Putin is certain to win a fourth term in Sunday's election, so voter apathy is widespread.
At polling station number 217 in Ust-Djeguta, two 18-year-old students case their ballots.
One incident was recorded in the town of Lyubertsy just outside Moscow.
Putin, 65, has been in power, either as president or prime minister, since 2000. I would have like to have had an option. "So when I saw your tweet... that raised my alarm".
Several Russians told CNN of a culture of pressure to support the President.
"Putin needs to finish what he started", he said.
There was little fanfare in the campaign period and Russian news was dominated by developments in political crises between Russia and Western powers.
Putin's re-election comes amid rising tension with the West, particularly with the United Kingdom, which last week accused Russian Federation of using a nerve agent to poison the former spy and his daughter living in England. Russian Federation denies the allegation, and both countries have since expelled diplomats over the row.
Russian Federation has also vowed to retaliate after the United States imposed new sanctions on the country this week over its reported cyberattacks and meddling in the 2016 presidential election. Russian Federation has vowed retaliation.
First polling stations welcomed early voters at 8:00 am local time [20:00 GMT] on Saturday in Kamchatka and Chukotka regions, followed by the island of Sakhalin an hour later.
Russia annexed Crimea from Ukraine four years ago, earning Putin admiration from many Russians and condemnation from the West.
Making 109 million voters eligible for voting the Presidential Election of Russian Federation began today (18 March). Ukraine security forces blocked the Russian Embassy in Kyiv and consulates elsewhere Sunday as the government protested the voting in Crimea, whose annexation is still not internationally recognized.
18 March 2018
17 March 2018
18 March 2018
