Ohtani, often compared to MLB great Babe Ruth because of his ability to pitch and hit at an elite level, was the unanimous pick over Toronto Blue Jays players Vladimir Guerrero Jr. and Marcus Semien in voting by the Baseball Writers' Association of America.
"MVP is something I was shooting for, obviously, I think any player is as long as they're playing baseball professionally," said Ohtani via a translator. "But I was more appreciative of the fact that American fans - just the USA baseball - was more accepting and welcoming (of) the whole two-way idea compared to when I first started in Japan.
"It made the transition a lot easier for me, so very thankful for that."
In his first full MLB season as both a hitter and pitcher, Ohtani had a .257 batting average, 46 home runs and 100 RBI to go along with a 9-2 record and 3.18 earned-run average in 23 starts on the mound.
The 27-year-old is the first Japanese player to win the award since Ichiro Suzuki earned the honours in 2001 as a member of the Seattle Mariners.