Last Updated on September 20, 2025 10:15 pm by Alex Becker
The Seattle Mariners remain in Houston to face the Astros at 7:00 PM ET. It’s Sunday Night Baseball on ESPN and the final game of a three-game set. Can the Astros win the game outright as money-line home underdogs? Keep reading for our Mariners vs. Astros betting prediction.
Projected starting pitchers: Logan Gilbert (SEA) vs. Jason Alexander (HOU)
The Seattle Mariners are 86-69 straight up this year. They are 9-1 straight up in their last 10 games. The Mariners are 66-89 ATS this season.
The Houston Astros are 84-71 straight up this year. They are 6-4 straight up in their last 10 games. The Astros are 74-81 ATS this season.
Mariners vs. Astros Game Matchup and Betting Odds
917 Seattle Mariners (-136) at 918 Houston Astros (+115); o/u 8.5
7:00 PM ET, Sunday, September 21, 2025
Daikin Park, Houston, TX
TV: ESPN
Mariners vs. Astros Public Betting Information
Our MLB Public Betting Information page indicates that 67% of public bettors are currently backing the Mariners money line. Please note that these numbers are subject to change all the way up to game time, so be sure to check the link to ensure that you’re receiving the most up-to-date public betting data.
Seattle Mariners DFS Spin
Mariners third baseman Eugenio Suarez reached base 3 times in his team’s 6-4 win over the Astros on Saturday night. In that game, the 2-time All-Star went 2 for 4 with 2 doubles, an RBI, a walk, and a run scored. For the season, Suarez is hitting .230 with 47 homers, 113 RBIs, 4 steals, and an OPS of .835 across 560 at-bats. Eugenio Suarez is batting .272 with an OPS of 1.118 while ahead in the count this season, making him an interesting DFS option on Sunday.
Houston Astros DFS Spin
Astros shortstop Jeremy Pena drove in all of his club’s runs in their 6-4 loss to the Mariners on Saturday. Hitting out of the leadoff spot, the 2022 World Series MVP went 2 for 4 with a homer, 4 RBIs, a walk, and a run scored. Pena is hitting .304 with 17 homers, 62 RBIs, 20 steals, and an OPS of .840 across 493 at-bats this year. The 2022 Gold Glove Award winner is batting .379 with an OPS of 1.128 over his last 7 games. That fact makes Jeremy Pena worth a look in most DFS formats on Sunday.
Mariners vs. Astros MLB Betting Trends
Seattle is 21-23 straight up as a road favorite this season.
Seattle is 38-42 straight up as the road team this season.
Houston is 46-34 straight up as the home team this season.
Houston is 5-2 straight up in their last 7 games overall.
Mariners vs. Astros Betting Prediction
I like Houston here. A few numbers will illustrate why. The Astros are 9-3 straight up as a home underdog and 29-20 straight up as an underdog this year. What’s more, Houston is 43-27 straight up after a loss and 75-59 straight up when playing on no rest in 2025. And finally, the Astros are 79-63 straight up when playing an opponent on equal rest and 11-1 straight up in starting pitcher Jason Alexander’s appearances for the team this season. The pick is Houston +115 on the money line over Seattle at Bovada.lv.