Jose Altuvi led the way with four RBI on four hits, including a two-run homer that staked Houston to a 13-0 lead.
The Astros came into the contest nursing a six-game losing streak, but were ahead 10-0 by the end of the third inning. Paul Clemens (1-0) was credited with the win in relief.
Chris Carter hit two home runs for Houston. J.D. Martinez and Marwin Gonzalez also knocked it out of the park.
Brandon Mauer (0-2) took the loss for Seattle. He lasted just 2/3 of the first inning and was shelled by six runs on seven hits and struck out two.
The Mariners outscored Houston 7-2 in the final three innings but came up short.