Ovechkin, who also claimed the MVP award in 2008 and 2009, edged Pittsburgh Penguins center Sidney Crosby in the closest Hart race in a decade.
Ovechkin received 1,090 points to 1,058 for Crosby in voting conducted by the Professional Hockey Writers' Association.
Crosby, however, did not go away empty-handed, capturing the Ted Lindsay award that goes to the most outstanding player as voted by his fellow players.
Ovechkin tallied 32 goals, including 23 in his final 23 contests, as he also became the first three-time winner of the Maurice "Rocket" Richard Trophy as the season's top goalscorer.
The 27-year-old Russian also finished third in points (56), first in power-play goals (16), first in power-play points (27) and first in shots on goal (220).
The New York Islanders' John Tavares finished third in the Hart Trophy voting.
Because of the lockout-shortened season, the NHL decided to hand out individual honors during the Stanley Cup rather than the usual glitzy awards ceremony held at the end of the season in Las Vegas.
Other winners included Florida Panthers center Jonathan Huberdeau who picked up the Calder Trophy as rookie of the year, edging Montreal Canadiens left wing Brendan Gallagher.
Selected third overall in the 2011 draft by Florida, Huberdeau played all 48 games in his debut campaign and recorded 14 goals and 31 points as the first Panther to earn rookie of the year honors.
Sergei Bobrovsky of the Columbus Blue Jackets was the runaway winner of the Vezina Trophy as the league's top netminder, easily outpointing runnerup Henrik Lundqvist of the New York Rangers.
Bobrovsky, who (21-11-6) backstopped Columbus's late-season surge, received 17 first-place and double the points of Lundqvist.
Montreal Canadiens P.K. Subban took home the James Norris Trophy awarded to the league's top defenseman.
In another close race, Subban, who topped defensemen in scoring with 38 points (11 goals, 27 assists) out-pointed Minnesota Wild's Ryan Sutter 1,266 points to 1,230.