"Like I said to everybody after the game, this is one of the most disappointing parts of the ... season," veteran catcher Martin Maldonado said. "This is a slap in the face and a wake-up call."
Sunday's win cut Houston's lead over Seattle to within a half-game. The Mariners currently hold the third AL wild-card playoff spot, with the Astros in the second spot and the Rangers atop the AL West with a three-game lead over Houston.
Maldonado said the Astros need to stop focusing on their opponents but instead on how they can play better.
"The key will be better energy in the dugout, not being satisfied after you lose," he said. "Everybody who comes here wants to beat us and we don't make them earn it. We just feel like we're just giving it away."
The Mariners jumped on Hunter Brown (9-9) early in Sunday's game, scoring two runs in each of the first three innings to race out to a 6-0 lead.
Seattle starter Emerson Hancock pitched two scoreless innings before leaving with a right shoulder strain. He was relieved by Tayler Saucedo, who allowed five runs without getting an out to cut the lead to 1.
Dylan Moore, who also set a career mark with four hits, pushed the lead to 7-5 with an RBI single in the fifth.
Sunday's victory extends Seattle's overall winning streak to six games and improves the team's record against Houston this season to 8-2.
The Associated Press contributed to this report.