The blast was Seattle's first leadoff homer this season and the second career leadoff homer for Smith. Smith previously went deep to open a game in Cincinnati on July 1, 2014, while playing for the Padres.
In the bottom of the first, it looked as though the Orioles would take the lead, but Smith made a leaping catch at the left-field wall to rob Baltimore's Adam Jones of a potential two-run home run.
With one out and a runner on first base, Jones sent a 92-mph fastball from Taijuan Walker to deep left that appeared destined for the first few rows of the bleachers.
Smith, though, tracked down the ball and reached over the seven-foot wall to come up with a spectacular catch.