He told cheering supporters in a triumphant but brief speech that "we are bound for success".
The election came amid escalating tensions with the West as Moscow was blamed for the nerve-agent poisoning this month of a former Russian double agent in Salisbury.
The incident came as Russian internet trolls were suspected of waging an extensive campaign to undermine the 2016 US presidential election.
Britain and Russia last week announced expulsions of diplomats over the spy case and the US issued new sanctions.
Moscow has denounced both cases as efforts to interfere in the Russian election.
But the disputes likely worked in Putin's favour, reinforcing the official stance that the West is infected with "Russophobia" and determined to undermine both Putin and traditional Russian values.
There had been no doubt that Mr Putin would win in his fourth electoral contest; he faced seven minor candidates and his most prominent foe was blocked from the ballot.
His only real challenge was to run up the tally so high that he could claim an indisputable mandate.
With ballots from 80% of Russia's precincts counted by early Monday, Mr Putin had amassed 76% of the vote.
Observers and individual voters reported widespread violations including ballot-box stuffing and forced voting, but the claims are unlikely to dilute the power of Russia's longest-serving leader since Josef Stalin.
As the embodiment of Russia's resurgent power on the world stage, Mr Putin commands immense loyalty among Russians.
More than 30,000 crowded into Manezh Square adjacent to the Kremlin in temperatures of minus 10C (15F) for a victory concert and to await his words.
Mr Putin extolled them for their support - "I am a member of your team" - and he promised them that "we are bound for success".
Then he left the stage after speaking for less than two minutes, a seemingly perfunctory appearance that encapsulated the election's predictability.
Since he took the helm in Russia on New Year's Eve 1999 after Boris Yeltsin's surprise resignation, Mr Putin's electoral power has centred on stability, a quality cherished by Russians after the chaotic breakup of the Soviet Union and the "wild capitalism" of the Yeltsin years.
But that stability has been bolstered by a suppression of dissent, the withering of independent media and the top-down control of politics called "managed democracy".
There were widespread reports of forced voting Sunday, efforts to make Russia appear to be a robust democracy.
Election officials moved quickly to respond to some of the violations.
Overall national turnout was expected to be a little more than 60%, which would be several points below turnout in Mr Putin's electoral wins in 2000, 2004 and 2012.
He did not run in 2008 because of term limits, but was appointed prime minister, a role in which he was widely seen as leader.
Mr Putin's most vehement foe, anti-corruption campaigner Alexei Navalny, was barred from running because he was convicted of fraud in a case widely regarded as politically motivated.
Mr Navalny and his supporters had called for an election boycott but the extent of its success could not immediately be gauged.
The election took place on the fourth anniversary of the 2014 annexation of Crimea from Ukraine, one of the most dramatic manifestations of Mr Putin's drive to reassert Russia's power.
Crimea and Russia's subsequent support of separatists in eastern Ukraine led to an array of US and European sanctions that, along with falling oil prices, damaged the Russian economy and slashed the ruble's value by half.
But Mr Putin's popularity remained strong, apparently buttressed by nationalist pride.
In his next six years, Mr Putin is likely to assert Russia's power abroad even more strongly.
Just weeks ago, he announced that Russia has developed advanced nuclear weapons capable of evading missile defences.
The Russian military campaign that bolsters the Syrian government is clearly aimed at strengthening Moscow's foothold in the Middle East, and Russia eagerly eyes any reconciliation on the Korean Peninsula as an economic opportunity.
At home, Mr Putin must face how to groom a successor or devise a strategy to circumvent term limits, how to diversify an economy still dependent on oil and gas, and how to improve medical care and social services in regions far removed from the cosmopolitan glitter of Moscow.