(Reuters) - LeBron James of the Miami Heat was named as Sports Illustrated's Sportsman of the Year for 2012, the U.S. magazine announced on Monday.

In an outstanding year, the 27-year-old James won his first NBA championship, his third league Most Valuable Player (MVP) award, was named MVP of the NBA finals and a won gold medal with the United States at the London Olympics.

He became just the sixth basketballer to win the award, which began in 1954. The most recent was his team-mate Dwyane Wade in 2006.

Two years ago, James became a hate figure for many American sports fans after he announced his decision to sign for Miami live on television after his contract with the Cleveland Cavaliers had expired.

He was booed at courts across the NBA and received intense criticism for his performance as Miami lost the 2011 NBA finals to the Dallas Mavericks.

"Did I think an award like this was possible two years ago? 'No, I did not," James said in an interview with the magazine.

"I thought I would be helping a lot of kids and raise $3 million by going on TV and saying, 'Hey, I want to play for the Miami Heat.' But it affected far more people than I imagined.

"I know it wasn't on the level of an injury or an addiction, but it was something I had to recover from. I had to become a better person, a better player, a better father, a better friend, a better mentor and a better leader. I've changed, and I think people have started to understand who I really am."

Previous winners of the award include swimmer Michael Phelps (2008), cyclist Lance Armstrong (2002) and golfer Tiger Woods (2000) while the first award was given to British athlete Roger Bannister in 1954 after he became the first person to run a mile in under four minutes.

(Reporting By Simon Evans; Editing by Julian Linden)