With 50% of the vote counted he had received 75% of the vote, the central election commission said.
The main opposition leader, Alexei Navalny, was barred from the race.
Addressing a rally in Moscow after the early results were declared, Mr Putin said voters had "recognised the achievements of the last few years".
The scale of victory - which had been widely predicted - appears to be a marked increase in his share of the vote from 2012, when he won 64%.