Mariners vs Royals Prediction, Odds, Moneyline, Spread & Over/Under for May 23

Odds updated as of 10:12 p.m.

The Seattle Mariners are among the MLB squads in action on Saturday, up against 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 (24-27) vs. Kansas City Royals (20-30)
• Date: Saturday, May 23, 2026
• Time: 4:10 p.m. ET
• Venue: Kauffman Stadium -- Kansas City, Missouri
• Coverage: Fox Sports 1, Royals.TV, and Mariners.TV

Mariners vs Royals Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: SEA: (-142) | KC: (+120)
• Spread: SEA: -1.5 (+118) | KC: +1.5 (-142)
• Total: 8.5 -- Over: (-122) | Under: (+100)

Mariners vs Royals Probable Starting Pitchers

Probable Pitchers: George Kirby (Mariners) - 5-3, 3.45 ERA vs Stephen Kolek (Royals) - 2-0, 4.24 ERA

The Mariners will call on George Kirby (5-3) versus the Royals and Stephen Kolek (2-0). Kirby's team is 5-5-0 against the spread in his starts this season. Kirby's team has won 60% of his starts when they are favored on the moneyline (6-4). The Royals have a 2-1-0 ATS record in Kolek's three starts that had a set spread. The Royals were the moneyline underdog for two Kolek starts this season -- they won both.

Mariners vs Royals Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Mariners win (59.4%)

Mariners vs Royals Moneyline

• Kansas City is a +120 underdog on the moneyline, while Seattle is a -142 favorite on the road.

Mariners vs Royals Spread

• The Royals are at +1.5 on the runline against the Mariners. The Royals are -142 to cover the spread, and the Mariners are +118.

Mariners vs Royals Over/Under

• The over/under for the Mariners versus Royals game on May 23 has been set at 8.5, with -122 odds on the over and +100 odds on the under.

Bet on Seattle Mariners vs. Kansas City Royals on FanDuel today!

Mariners vs Royals Betting Trends

• The Mariners have been chosen as favorites in 47 games this year and have walked away with the win 23 times (48.9%) in those games.
• This season Seattle has come away with a win 14 times in 25 chances when named as a favorite of at least -142 on the moneyline.
• The Mariners and their opponents have gone over in 23 of their 51 games with a total set by sportsbooks this season.
• The Mariners are 18-33-0 against the spread in their 51 games that had a posted line this season.
• The Royals have put together an 8-14 record in games they were listed as the moneyline underdog (winning 36.4% of those games).
• Kansas City has a record of 2-3 when it has played as a moneyline underdog with odds of +120 or longer (40%).
• The Royals have combined with opponents to go over the total 21 times this season for a 21-26-0 record against the over/under.
• The Royals are 20-27-0 against the spread this season.

Mariners Player Leaders

• Randy Arozarena leads Seattle in OBP (.393), slugging percentage (.467) and total hits (55) this season. He has a .302 batting average.
• Among qualified hitters in the majors, he ranks 14th in batting average, 12th in on-base percentage, and 47th in slugging.
• Julio Rodriguez is batting .256 with 10 doubles, eight home runs and 17 walks. He's slugging .424 with an on-base percentage of .320.
• He is 75th in batting average, 97th in on-base percentage and 72nd in slugging among qualifying hitters.
• Rodriguez enters this game looking to extend his three-game hit streak. During his last five outings he is hitting .250 with a double, a home run, a walk and an RBI.
• Josh Naylor has 47 hits this season and has a slash line of .250/.317/.356.
• J.P. Crawford has been key for Seattle with 30 hits, an OBP of .358 plus a slugging percentage of .364.

Royals Player Leaders

• Bobby Witt Jr. has put up an on-base percentage of .369, a slugging percentage of .482, and has 59 hits, all club-bests for the Royals (while batting .299).
• Including all the qualified hitters in MLB, he ranks 15th in batting average, 31st in on-base percentage and 35th in slugging percentage.
• Witt brings a three-game hitting streak into this matchup. During his last five outings he is batting .211 with a double and a walk.
• Maikel Garcia has 13 doubles, a triple, three home runs and 19 walks while hitting .255. He's slugging .380 with an on-base percentage of .319.
• Including all qualifying players, his batting average puts him 77th, his on-base percentage is 100th, and he is 105th in slugging.
• Vinnie Pasquantino has four doubles, two triples, five home runs and 21 walks while batting .194.
• Salvador Perez has five doubles, eight home runs and nine walks while batting .211.

Mariners vs Royals Head to Head

• 5/3/2026: 4-1 KC (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -116, Underdog Moneyline: -102)
• 5/2/2026: 3-2 KC (Favorite: Mariners, Spread: -1.5, Total: 8, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 5/1/2026: 7-6 KC (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -148, Underdog Moneyline: +126)
• 9/18/2025: 2-0 SEA (Favorite: Mariners, Spread: -1.5, Total: 9, Favorite Moneyline: -120, Underdog Moneyline: +102)
• 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)

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