James became the first NBA player to score 30 points while shooting 60 percent in six straight games on Tuesday but was unable to extend the record to seven against the Thunder, his percentage dipping to 58 on 14-for-24 shots.
With the NBA approaching the mid-season All Star break, James passed the 30-point mark for the seventh game in a row and also had 12 rebounds and seven assists in the Valentine's Day showdown between last year's NBA finalists.
Kevin Durant scored 40 points for the Thunder but the result of the game was never in doubt after the Heat opened up a big lead in Oklahoma.
The Heat (36-14) led by as much as 23 points in the third quarter and while Oklahoma (39-14) cut the deficit to single figures in the final quarter Miami ran out comfortable winners.
Miami's Chris Bosh scored 20 points and had 12 rebounds while Dwayne Wade chipped in with 13 points before fouling out.
It was the Heat's seventh straight win and their sixth in a row over the Thunder, including last season's NBA finals.
The Heat currently led the Eastern Conference while Oklahoma, who had won four games in a row by 20 points or more before losing their last two, are second to San Antonio (42-12) in the Western Conference.
The NBA will break for four days starting from Friday for the annual All Star game, to be played this year in Houston.