James, who became the fifth player in league history to claim at least four MVP awards, polled 120 of the 121 first-place votes cast for a total of 1,207 points.
The 28-year-old finished far ahead of Oklahoma City's Kevin Durant, who tallied 93 second-place votes for a total of 765 points.
New York's Carmelo Anthony came in third with 732 points, collecting the one first-place vote that didn't go to James.
James led the defending NBA champion Heat to a franchise-record 66 regular season victories in 2012-13, averaging 26.8 points, 8.0 rebounds and 7.3 assists per game.
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