The Houston Astros are road underdogs to the Seattle Mariners ahead of their 10:10 p.m. ET first pitch at T-Mobile Park on Wednesday, Sept. 23.
My top Astros vs. Mariners predictions and MLB picks call for Houston to pull off the upset and make it consecutive wins over Seattle tonight.
Who will win Astros vs Mariners today: Astros moneyline
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With the Houston Astros battling for a postseason berth, and Seattle Mariners righty George Kirby collapsing down the stretch, the Astros moneyline is in play for me to 50%.
Kirby has ballooned to a 5.32 xERA and 4.37 xFIP over his past seven starts after posting respective 3.89 and 3.80 marks to start the season, after all. He’s allowed a healthy 37.8% hard-hit rate and .359 on-base percentage across five starts against the Astros that past two years, too
Additionally, the Seattle lineup will see rookie Ethan Pecko for the first time, and he’s held opposing hitters to a minuscule 27.3% hard-hit rate to go along with a solid 3.01 xERA across his past three appearances.
COVERS INTEL: The Seattle Mariners have the third-lowest wOBA in baseball, including a 23rd-ranked mark at home against right-handed pitchers.
Astros vs Mariners Over/Under pick: Over 7.5
In addition to Houston being set up for success against Kirby, Seattle has also shown off offensively with a ninth-ranked wOBA and 10th-ranked xwOBA over the past two weeks.
Additionally, the Houston bullpen has been tasked with 18 1/3 innings across the past four games, and Astros relievers sport a concerning 4.41 xERA and 5.05 xFIP during the busy stretch.
As a result, I’m anticipating the Mariners also putting runs on the board to send this total Over the number, and I recommend it to 53.5%
Astros vs Mariners home run prediction: Yordan Alvarez
Houston superstar Yordan Alvarez sports a third-ranked .311 ISO against right-handed pitchers among qualified hitters and has already homered off Kirby earlier this season. Additionally, Kirby has allowed a massive 43.2% squared-up contact rate and 18.6% blast-contact rate to left-handed hitters during the highlighted seven-start slump.
- ML/RL picks: 63-35, +31.08 units
- Over/Under picks: 36-33, 0.55 units
Astros vs Mariners weather
The forecast calls for clear, cool night skies at T-Mobile Park with temperatures dropping to 63°F, and a gentle 5 mph breeze blowing in from left field.
Astros vs Mariners odds
- Moneyline: Astros 44% | Mariners 57%
- Run line: Astros +1.5 (62%) | Mariners -1.5 (40%)
- Over/Under: Over 7.5 (54%) | Under 7.5 (49%)
Astros vs Mariners trend
The Houston Astros have WON 30 of their last 50 away games (+11.70 Units / 22% ROI). Find more MLB betting trends for Astros vs. Mariners.
How to watch Astros vs Mariners and game info
| Location | T-Mobile Park, Seattle, WA |
| Date | Wednesday, September 23, 2026 |
| First pitch | 10:10 p.m. ET |
| TV | ESPN |
| Astros starting pitcher | Ethan Pecko (1-0, 3.77 ERA) |
| Mariners starting pitcher | George Kirby (9-11, 4.24 ERA) |
Astros vs Mariners latest injuries
Odds are correct at the time of publishing and are subject to change.
Not intended for use in MA.
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