Center-fielder Trout, 21, hit .326 with 30 homers and 83 RBIs since his call-up from the minor leagues in late April.
Trout received all 28 first-place votes from the Baseball Writers' Association of America and was the eighth unanimous AL pick and the first since Tampa Bay's Evan Longoria in 2008.
The National League Rookie of the Year was scheduled to be announced Monday night.
The Associated Press contributed to this report.
