Astros vs Mariners Prediction, Odds, Moneyline, Spread & Over/Under for Sept. 20

Odds updated as of 7:12 p.m.

In MLB action on Saturday, the Houston Astros face the Seattle Mariners.

We've got you covered, in terms of the vital information regarding this matchup before you take a look at the MLB odds and spreads on FanDuel Sportsbook.

Astros vs Mariners Game Info

• Houston Astros (84-70) vs. Seattle Mariners (85-69)
• Date: Saturday, September 20, 2025
• Time: 7:10 p.m. ET
• Venue: Daikin Park -- Houston, Texas
• Coverage: SCHN and ROOT Sports NW

Astros vs Mariners Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: HOU: (-108) | SEA: (-108)
• Spread: HOU: +1.5 (-188) | SEA: -1.5 (+155)
• Total: 7.5 -- Over: (-100) | Under: (-122)

Astros vs Mariners Probable Starting Pitchers

Probable Pitchers: Framber Valdez (Astros) - 12-10, 3.59 ERA vs George Kirby (Mariners) - 9-7, 4.46 ERA

The probable pitchers are Framber Valdez (12-10) for the Astros and George Kirby (9-7) for the Mariners. Valdez and his team have a record of 11-17-0 against the spread when he starts. Valdez's team has a record of 12-11 this season when he starts and they are the favorite on the moneyline. The Mariners are 8-11-0 against the spread when Kirby starts. The Mariners were the underdog on the moneyline for two Kirby starts this season -- they split the games.

Astros vs Mariners Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Mariners win (57.6%)

Astros vs Mariners Moneyline

• Seattle is a -108 underdog on the moneyline, while Houston is a -108 favorite at home.

Astros vs Mariners Spread

Astros vs Mariners Over/Under

• A total of 7.5 runs has been set for the Astros-Mariners game on Sept. 20, with the over available at -100 and the under at -122.

Bet on Houston Astros vs. Seattle Mariners on FanDuel today!

Astros vs Mariners Betting Trends

• The Astros have won in 50, or 53.2%, of the 94 contests they have been named as odds-on favorites in this year.
• This season Houston has come away with a win 51 times in 98 chances when named as a favorite of at least -108 on the moneyline.
• The Astros and their opponents have hit the over in 69 of their 153 games with a total set by oddsmakers this season.
• In 153 games with a line this season, the Astros have a mark of 77-76-0 against the spread.
• The Mariners have an 18-21 record in games they were the underdog on the moneyline (winning 46.2% of those games).
• When playing as a moneyline underdog with odds of -108 or longer, Seattle has an 18-21 record (winning 46.2% of its games).
• The Mariners have played in 149 games with an over/under set, and have combined with their opponents to go over the total 80 times (80-64-5).
• The Mariners have collected a 66-83-0 record against the spread this season (covering 44.3% of the time).

Astros Player Leaders

• Jose Altuve leads Houston with a slugging percentage of .441, fueled by 49 extra-base hits. He has a .261 batting average and an on-base percentage of .322.
• Among qualifying batters in the majors, he is 61st in batting average, 87th in on-base percentage, and 67th in slugging.
• Jeremy Pena leads Houston in OBP (.361), slugging percentage (.470) and total hits (148) this season. He's batting .303.
• Among qualifying hitters, his batting average places him sixth, his on-base percentage 18th, and his slugging percentage 41st.
• Yainer Diaz has 131 hits this season and has a slash line of .256/.285/.416.
• Carlos Correa is batting .276 with a .330 OBP and 50 RBI for Houston this season.
• Correa enters this game on a four-game hitting streak. During his last five outings he is batting .300 with two doubles and a walk.

Mariners Player Leaders

• Cal Raleigh has racked up 139 hits with a .360 on-base percentage, leading the Mariners in both categories. He's batting .246 and slugging .583.
• Including all the qualifying players in the majors, his batting average ranks 99th, his on-base percentage is 21st, and he is third in slugging.
• Julio Rodriguez paces his team with a .479 slugging percentage. He has a batting average of .269 with an on-base percentage of .321.
• He is currently 40th in batting average, 91st in on-base percentage and 32nd in slugging percentage among all qualifying hitters.
• Josh Naylor is hitting .289 with 26 doubles, a triple, 20 home runs and 47 walks.
• Eugenio Suarez is batting .228 with 26 doubles, 47 home runs and 44 walks.

Astros vs Mariners Head to Head

• 9/19/2025: 4-0 SEA (Favorite: Astros, Spread: -1.5, Total: 7.5, Favorite Moneyline: -108, Underdog Moneyline: -108)
• 7/20/2025: 11-3 HOU (Favorite: Mariners, Spread: -1.5, Total: 6.5, Favorite Moneyline: -144, Underdog Moneyline: +122)
• 7/19/2025: 7-6 SEA (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -132, Underdog Moneyline: +112)
• 7/18/2025: 6-1 SEA (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 5/25/2025: 5-3 HOU (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -138, Underdog Moneyline: +118)
• 5/24/2025: 2-1 HOU (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -110, Underdog Moneyline: -106)
• 5/23/2025: 5-3 SEA (Favorite: Astros, Spread: -1.5, Total: 8.5, Favorite Moneyline: -116, Underdog Moneyline: -102)
• 5/22/2025: 9-2 HOU (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -132, Underdog Moneyline: +112)
• 4/9/2025: 7-6 SEA (Favorite: Astros, Spread: -1.5, Total: 7.5, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 4/8/2025: 2-1 HOU (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -120, Underdog Moneyline: +102)

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