Trout's blast came in the third inning of the setback on Sunday at Oriole Park at Camden Yards in Baltimore.
Orioles first baseman Chris Davis blasted a solo shot off of Angels starter Griffin Canning to leadoff the bottom of the second inning. Orioles center fielder Stevie Wilkerson added to the lead with a solo shot two at-bats later.
Trout came up to leadoff the third frame against Orioles starter John Means. The left-handed pitcher fell behind 2-0 in the count, before getting a called strike on Trout. Trout fouled off Mean's fourth offering of the exchange.
Means lobbed in a 79.7 mph changeup for his final pitch to Trout. The Angels star belted the pitch to center field.
Trout's solo shot had an exit velocity of 106.1 mph and a launch angle of 26.7 degrees, according to Statcast. He is now hitting .283 with nine home runs and 25 RBIs this season for the Angels.
Dwight Smith Jr. added to Baltimore's lead with a two-run homer in the bottom of the third inning. Pedro Severino went yard for the fifth time this season with a solo home run in the bottom of the sixth inning for the Orioles.
Trout was 1-for-2 on the day with two walks, a run scored and an RBI in the loss.
The Orioles face the New York Yankees in the first clash of a three-game American League East series at 6:35 p.m. on Monday at Yankee Stadium in New York City.