Canadian-born Gilgeous-Alexander pipped Nikola Jokic of the Denver Nuggets to the prize, which considers only performances during the regular season.
Broadcasters TNT said that Gilgeous-Alexander won the vote 71-29 over Serbian Jokic, who has won the MVP award three times.
Gilgeous-Alexander, who finished second to Jokic last year, shot almost 52 percent from the field as he led the Thunder to the best record in the league. Oklahoma City won 68 games and set a league record for scoring margin.
“You try so hard throughout the season to not think about it and just worry about playing basketball and getting better and trying to win games,” Gilgeous-Alexander said.
“But as a competitor, as a kid dreaming about the game, it’s always in the back of your mind and I am very grateful to be on this side of the ballot,” he added.
Gilgeous-Alexander led the league with 32.7 points per and also averaged 6.4 assists and 5.0 rebounds.
The 26-year-old can yet crown his season with a championship with the Thunder 1-0 up in their Western Conference final against the Minnesota Timberwolves.
Gilgeous-Alexander was quick to praise his team-mates for their role in the individual honour.
“None of it is possible without the guys behind me. The amount of games we won and the fashion that we won the games is so impressive and it’s probably the main reason why I get the award,” he said.
The last US-born player to win was James Harden in 2018. (AFP)
