Trout became a father last week and had been on paternity leave, but returned to the lineup for the Angels' 5-3 win Tuesday at T-Mobile Park in Seattle.
The three-time American League MVP settled in against Mariners starter Justin Dunn in the second at-bat of the game. He took a called strike before he evened the count at 2-2.
Dunn then lobbed in an 82.7-mph slider. Trout pounced on the pitch and sent it to center field for a 407-foot solo home run. The blast traveled at 107 mph and left the field in 4.1 seconds, according to Statcast.
Austin Nola hit an RBI triple in the bottom of the sixth frame to put the Mariners on the board. David Fletcher then hit a two-run homer in the top of the next inning to give the Angels a 5-1 edge. Dylan Moore hit a solo shot for the Mariners in the bottom of the seventh frame.
Nola then plated Kyle Lewis for the Mariners' final run with an RBI single in the bottom of the eighth inning.
Angels starter Andrew Heaney allowed three hits and one run in 5 2/3 innings to pick up his first win of the season. Dunn allowed three hits and three runs to take the loss.
Trout went 1 for 3 with an RBI, a run scored and a walk for the Angels. Fletcher and Pujols collected two RBIs apiece in the win. Nola went 2 for 3 with two RBIs and a walk for Seattle.
Trout is now hitting .296 with two home runs and five RBIs this season. His new son, Beckham Aaron Trout, was born at 8:10 p.m. EDT Thursday.
"A lot of emotions going into it," Trout told reporters. "I didn't really know what to expect but, once I got to see him and hold him with Jess (Trout's wife) and seeing how she was feeling, what we went through to have a child. It's pretty amazing."
The Angels (4-7) next battle the Mariners (4-8) in the second game of the three-game series at 9:40 p.m. EDT Wednesday in Seattle.