Mariners vs Royals Prediction, Odds, Moneyline, Spread & Over/Under for Sept. 18

Odds updated as of 9:12 p.m.
The Seattle Mariners are among the MLB teams in action on Thursday, versus the Kansas City Royals.
Here's what you need to know before checking out today's MLB odds and spreads on FanDuel Sportsbook.
Mariners vs Royals Game Info
- Seattle Mariners (83-68) vs. Kansas City Royals (75-76)
- Date: Thursday, September 18, 2025
- Time: 2:10 p.m. ET
- Venue: Kauffman Stadium -- Kansas City, Missouri
- Coverage: FDSKC and ROOT Sports NW
Mariners vs Royals Odds & Moneyline
- All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
- Moneyline: SEA: (-130) | KC: (+110)
- Spread: SEA: -1.5 (+116) | KC: +1.5 (-140)
- Total: 9 -- Over: (-110) | Under: (-110)
Mariners vs Royals Probable Starting Pitchers
Probable Pitchers: Luis Castillo (Mariners) - 9-8, 3.76 ERA vs Michael Lorenzen (Royals) - 5-11, 4.95 ERA
This contest's pitching matchup is set, as the Mariners will send Luis Castillo (9-8) to the mound, while Michael Lorenzen (5-11) will take the ball for the Royals. Castillo and his team have a record of 13-17-0 against the spread when he starts. When Castillo starts a game and his team is the favorite on the moneyline, they have a record of 13-10. The Royals have gone 14-10-0 against the spread when Lorenzen starts. The Royals have been the moneyline underdog in 14 of Lorenzen's starts this season, and they went 7-7 in those matchups.
Mariners vs Royals Prediction & Pick
All MLB win probability predictions and picks are according to numberFire.
Prediction: Mariners win (58.4%)
Mariners vs Royals Moneyline
- Seattle is a -130 favorite on the moneyline, while Kansas City is a +110 underdog at home.
Mariners vs Royals Spread
- The Royals are +1.5 on the spread (-140 to cover), and Seattle is +116 to cover the runline.
Mariners vs Royals Over/Under
- The over/under for Mariners-Royals on Sept. 18 is 9. The over is -110, and the under is -110.
Bet on Seattle Mariners vs. Kansas City Royals on FanDuel today!
Mariners vs Royals Betting Trends
- The Mariners have been victorious in 61, or 58.7%, of the 104 contests they have been chosen as favorites in this season.
- This season Seattle has come away with a win 49 times in 75 chances when named as a favorite of at least -130 on the moneyline.
- The Mariners and their opponents have gone over the total this season in 79 of their 146 opportunities.
- The Mariners are 64-82-0 against the spread in their 146 games that had a posted line this season.
- The Royals have won 39 of the 87 games they were the underdog on the moneyline this season (44.8%).
- Kansas City has a 21-32 record (winning just 39.6% of its games) when playing as a moneyline underdog of +110 or longer.
- The Royals have had an over/under set by oddsmakers 149 times, and have combined with opponents to go over the total in 64 of those games (64-83-2).
- The Royals have covered 48.3% of their games this season, going 72-77-0 ATS.
Mariners Player Leaders
- Cal Raleigh leads Seattle in OBP (.361) and total hits (137) this season. He's batting .247 batting average while slugging .590.
- Among all qualified batters, he is 99th in batting average, his on-base percentage ranks 17th, and he is third in slugging.
- Raleigh will look for his fifth straight game with a hit in this matchup. During his last five outings he is hitting .444 with three doubles, three home runs, five walks and five RBIs.
- Julio Rodriguez leads Seattle in slugging percentage (.480) thanks to 65 extra-base hits. He's batting .271 with an on-base percentage of .323.
- His batting average ranks 37th among qualified players, his on-base percentage 87th, and his slugging percentage 31st.
- Rodriguez has picked up at least one hit in six straight games. During his last 10 outings he is hitting .390 with seven doubles, two home runs, four walks and 11 RBIs.
- Josh Naylor is batting .283 with a .449 slugging percentage and 86 RBI this year.
- Naylor heads into this matchup with three games in a row with at least one hit. In his last five games he is batting .217 with a double, a walk and six RBIs.
- Eugenio Suarez has 45 home runs, 109 RBI and a batting average of .224 this season.
Royals Player Leaders
- Bobby Witt Jr. has 167 hits with a .500 slugging percentage, both team-high figures for the Royals. He's batting .292 and with an on-base percentage of .352.
- Including all the qualified hitters in the big leagues, his batting average places him 12th, his on-base percentage ranks 35th, and he is 17th in slugging.
- Maikel Garcia paces his team with a .354 OBP. He has a batting average of .289 while slugging .458.
- Including all qualifying hitters, he ranks 14th in batting average, 32nd in on-base percentage and 51st in slugging percentage.
- Vinnie Pasquantino has 27 doubles, a triple, 30 home runs and 45 walks while hitting .263.
- Salvador Perez is batting .237 with 34 doubles, 28 home runs and 23 walks.
Mariners vs Royals Head to Head
- 9/16/2025: 12-5 SEA (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -136, Underdog Moneyline: +116)
- 7/3/2025: 3-2 KC (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -120, Underdog Moneyline: +102)
- 7/2/2025: 3-2 SEA (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -166, Underdog Moneyline: +140)
- 7/1/2025: 6-3 KC (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -138, Underdog Moneyline: +118)
- 6/30/2025: 6-2 SEA (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -164, Underdog Moneyline: +138)
- 6/9/2024: 6-5 SEA (Favorite: Royals, Spread: -1.5, Total: 7.5, Favorite Moneyline: -136, Underdog Moneyline: +116)
- 6/8/2024: 8-4 KC (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -134, Underdog Moneyline: +114)
- 6/7/2024: 10-9 KC (Favorite: Mariners, Spread: -1.5, Total: 9, Favorite Moneyline: -122, Underdog Moneyline: +104)
- 5/15/2024: 4-2 SEA (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -142, Underdog Moneyline: +120)
- 5/14/2024: 4-2 KC (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -164, Underdog Moneyline: +138)
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