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

Odds updated as of 2:12 a.m.

The Houston Astros are among the MLB teams in action on Saturday, versus the Seattle Mariners.

Before you do any MLB betting on this game at FanDuel Sportsbook, here's everything you need to know.

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: (-116) | SEA: (-102)
• Spread: HOU: +1.5 (-192) | SEA: -1.5 (+155)
• Total: 8 -- 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's team is 11-17-0 against the spread this season in his starts. Valdez's team has won 52.2% of his starts when they are favored on the moneyline (12-11). The Mariners have an 8-11-0 ATS record in Kirby's 19 starts that had a set spread. The Mariners were named the moneyline underdog 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: Astros win (51.8%)

Astros vs Mariners Moneyline

• The Astros vs Mariners moneyline has Houston as a -116 favorite, while Seattle is a -102 underdog on the road.

Astros vs Mariners Spread

• The Mariners are 1.5-run favorites against the spread for this matchup with the Astros. The Mariners are +155 to cover, while the Astros are -192 to cover as a 1.5-run underdog on the runline.

Astros vs Mariners Over/Under

• Astros versus Mariners, on Sept. 20, has an over/under of 8, with the over being -100 and the under -122.

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

Astros vs Mariners Betting Trends

• The Astros have been victorious in 50, or 53.2%, of the 94 contests they have been chosen as favorites in this season.
• This season Houston has come away with a win 47 times in 89 chances when named as a favorite of at least -116 on the moneyline.
• The Astros' games have gone over the total in 69 of their 153 opportunities.
• In 153 games with a line this season, the Astros have a mark of 77-76-0 against the spread.
• The Mariners have gone 18-21 in games they were the underdog on the moneyline (winning 46.2% of those games).
• Seattle has a 17-17 record (winning 50% of its games) when it has played as a moneyline underdog of -102 or longer.
• In the 149 games oddsmakers have set an over/under for the Mariners, they have combined with opponents to go over the total 80 times (80-64-5).
• The Mariners have gone 66-83-0 ATS this season.

Astros Player Leaders

• Jose Altuve has an OPS of .763, fueled by an OBP of .322 and a team-best slugging percentage of .441 this season. He has a .261 batting average.
• He ranks 61st in batting average, 87th in on-base percentage, and 66th in slugging among qualifying batters in baseball.
• Jeremy Pena leads Houston with 148 hits and an OBP of .361, plus a team-best slugging percentage of .470. He's batting .303.
• Among qualifying batters, he ranks sixth in batting average, 18th in on-base percentage and 40th in slugging percentage.
• Yainer Diaz has 131 hits this season and has a slash line of .256/.285/.416.
• Carlos Correa has 13 home runs, 50 RBI and a batting average of .276 this season.
• Correa heads into this matchup 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 put up an on-base percentage of .360 and has 139 hits, both team-best figures for the Mariners. He's batting .246 and slugging .583.
• He is 99th in batting average, 21st in on-base percentage and third in slugging percentage among all qualified batters in the majors.
• 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 ranks 40th in batting average, 91st in on-base percentage and 32nd in slugging percentage in MLB.
• Josh Naylor is hitting .289 with 26 doubles, a triple, 20 home runs and 47 walks.
• Eugenio Suarez is hitting .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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