Miami Heat clinched their second NBA title by routing Oklahoma City 121-106 on Thursday thanks to a balanced, offensive attack and 26 points, 13 assists and 11 re-bounds from superstar LeBron James.

James was named the Most Valuable Player of the NBA Finals after leading the Heat to the crown, capturing his long-sought first championship and delivering on the promise he made to the Miami fans when he joined the team two years ago.

Mike Miller came off the bench to sink 7-of-8 shots from three-point range and finish with 23 points while Chris Bosh added 24 points for Miami, who won the best-of-seven series 4-1 and claim their first title since 2006.

“I got a lot more grey hairs but this one is so gratifying,” said Miami coach Erik Spoelstra.

“We knew we had the confi-dence in what we could do but it would be a long season and it would be a tough road.

“We kept saying all year long it would be the toughest thing we’d have to do in our professional lives to get back to here and finally get those four wins,” the coach added.

This was James’s third trip to the NBA Finals, including one with Cleveland Cavaliers, but his first title in his nine years in the NBA.

Miami used impressive three-point shooting, hitting 14-of-26 from beyond the arc in front of a sold-out crowd of 20,003 at the American Airlines Arena.

Miami Heat also shot 58 per cent from the field in the first quarter on Thursday and never eased up on the Thunder, opening a huge lead with a explosive third quarter, outscoring Oklahoma City 36-22.

Three-time NBA scoring champion Kevin Durant finished with a game-high 32 points and 11 rebounds and guard Russell Westbrook had 19 points and six assists for the Thunder, who were blown out after losing three contests in a row by close margins heading into game five.

James showed no effects of the painful leg cramps he had to battle on Tuesday, knocking down the go-ahead three-pointer late in the fourth quarter on the way to a 104-98 victory.