The Japanese-born Ohtani received all 30 first-place votes in balloting by eligible Baseball Writers' Association of America (BBWAA) voters to beat out Corey Seager and Marcus Semien of the Texas Rangers.
He is the first player to win the MVP Award unanimously more than once, having also done so in 2021.
Ohtani, who is often compared to MLB great Babe Ruth because of his ability to pitch and hit at an elite level, produced an AL-leading 44 home runs, with 20 stolen bases and 95 RBIs with the Los Angeles Angels in 2023.
In 23 starts on the mound, Ohtani had a 3.14 ERA with 167 strikeouts, though his pitching season was cut short in August due to a torn ligament in his right elbow. A subsequent side strain ended his season entirely in September.
Ohtani finished second in voting last year behind New York Yankees slugger Aaron Judge.
"Obviously I wanted to win last year but Judge had a spectacular season and, deservedly so, he won it. So I wanted to come back stronger and try to win this year," Ohtani said via an interpreter. "My goal was to try to come out on top."
In Japan, where Ohtani began his professional career with the Nippon-Ham Fighters, chief government spokesperson Hirokazu Matsuno expressed "heartfelt respect" for his achievement.
"We are very happy to hear this bright news," Matsuno told reporters. "We look forward to seeing more of Otani's success in the future."
Ohtani, a three-time MLB All-Star and the most coveted free agent in recent memory, is expected to be able to hit without restrictions next season and to pitch again in 2025.
While Ohtani's win was all but a foregone conclusion, Atlanta Braves outfielder Ronald Acuna triumphed over a pair of Los Angeles Dodgers teammates in what was expected to be a more competitive race for the National League's Most Valuable Player.
But Acuna also won by unanimous vote, marking the first time in BBWAA voting that the winners in both leagues were unanimous in the same year, as he beat out the Dodgers' Mookie Betts and Freddie Freeman for the honor.
The Venezuelan four-times All-Star powered the Braves to a staggering 104 wins as he produced an NL-leading 149 runs, 217 hits and 73 stolen bases.
