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

Odds updated as of 1:13 p.m.

The Thursday slate in MLB includes a matchup between the Seattle Mariners and the Kansas City Royals.

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

Mariners vs Royals Game Info

• Seattle Mariners (83-69) vs. Kansas City Royals (76-76)
• 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: (-120) | KC: (+102)
• Spread: SEA: -1.5 (+134) | KC: +1.5 (-162)
• Total: 9 -- Over: (-120) | Under: (-102)

Mariners vs Royals Probable Starting Pitchers

Probable Pitchers: Luis Castillo (Mariners) - 9-8, 3.76 ERA vs Stephen Kolek (Royals) - 5-5, 3.71 ERA

This contest's pitching matchup is set, as the Mariners will send Luis Castillo (9-8) to the mound, while Stephen Kolek (5-5) will get the nod for the Royals. Castillo and his team are 13-17-0 ATS this season 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 are 12-5-0 against the spread when Kolek starts. The Royals are 4-6 in Kolek's 10 starts this season that they were the underdog on the moneyline.

Mariners vs Royals Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Mariners win (55.4%)

Mariners vs Royals Moneyline

• Looking at the moneyline for Royals-Mariners, Kansas City is the underdog at +102, and Seattle is -120 playing on the road.

Mariners vs Royals Spread

• The Royals are at +1.5 on the runline against the Mariners. The Royals are -162 to cover the spread, and the Mariners are +134.

Mariners vs Royals Over/Under

• Mariners versus Royals on Sept. 18 has an over/under of 9 runs, with the odds on the over -120 and the under set at -102.

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 54 times in 88 chances when named as a favorite of at least -120 on the moneyline.
• The Mariners and their opponents have gone over in 80 of their 147 games with a total set by sportsbooks this season.
• The Mariners have an against the spread mark of 64-83-0 in 147 games with a line this season.
• The Royals have won 44.8% of the games this season they were the underdog on the moneyline (39-48).
• Kansas City is 25-40 (winning only 38.5% of its games) when it has played as a moneyline underdog of +102 or longer.
• The Royals have combined with opponents to hit the over on the total 65 times this season for a 65-83-2 record against the over/under.
• The Royals have collected a 73-77-0 record against the spread this season (covering 48.7% of the time).

Mariners Player Leaders

• Cal Raleigh leads Seattle in OBP (.360) and total hits (138) this season. He's batting .247 batting average while slugging .588.
• Among qualifying batters in the majors, he is 97th in batting average, 20th in on-base percentage, and third in slugging.
• Raleigh will look for his sixth straight game with a hit in this contest. During his last five outings he is hitting .474 with three doubles, three home runs, two walks and five RBIs.
• Julio Rodriguez has an OPS of .801, fueled by an OBP of .323 and a team-best slugging percentage of .478 this season. He's batting .271.
• He ranks 37th in batting average, 86th in on-base percentage and 31st in slugging among qualifying hitters.
• Rodriguez brings a seven-game streak with at least one hit into this matchup. In his last 10 games he is hitting .350 with seven doubles, four walks and seven RBIs.
• Josh Naylor has 147 hits this season and has a slash line of .285/.344/.450.
• Naylor has logged a hit or more in four games in a row. In his last five games he is hitting .273 with a double and six RBIs.
• Eugenio Suarez has been key for Seattle with 126 hits, an OBP of .302 plus a slugging percentage of .528.

Royals Player Leaders

• Bobby Witt Jr. has a team-best OBP (.353) and slugging percentage (.501), and paces the Royals in hits (169, while batting .293).
• Including all qualified hitters, he is 12th in batting average, while his on-base percentage is 33rd and he is 15th in slugging.
• Witt heads into this game on a three-game hitting streak. During his last five outings he is batting .300 with a double, a triple, a home run, two walks and three RBIs.
• Maikel Garcia has a .353 on-base percentage to pace his team. He has a batting average of .289 while slugging .457.
• Including all qualified hitters, he is 13th in batting average, 33rd in on-base percentage and 53rd in slugging percentage.
• Vinnie Pasquantino is hitting .264 with 27 doubles, a triple, 30 home runs and 45 walks.
• Salvador Perez is hitting .238 with 34 doubles, 29 home runs and 25 walks.

Mariners vs Royals Head to Head

• 9/17/2025: 7-5 KC (Favorite: Royals, Spread: -1.5, Total: 8.5, Favorite Moneyline: -124, Underdog Moneyline: +106)
• 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)

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