Royals at Mariners odds, picks and predictions

The Kansas City Royals (14-19) and Seattle Mariners (16-18) play Sunday the final game of their 3-game series in Seattle, Washington. First pitch from T-Mobile Park is at 4:10 p.m. ET. Let’s analyze MLB odds around the Royals vs. Mariners odds and make our expert MLB picks and predictions for the best bets.

Season series: Royals 2-0

The Royals have won 6 of their last 8 games and are looking to complete the 3-game sweep over the Mariners. After a 7-6 win in the opener on Friday, they beat the Mariners 3-2 on Saturday in 10 innings, tying the game in the top of the ninth with OF Jac Caglianone’s RBI single off Mariners closer Andres Munoz, and then scored the game-winning run on a sacrifice fly in the 10th. SP Seth Lugo went 6 innings, allowing 2 runs on 7 hits and 2 walks, striking out 6.

The Mariners squandered a 14-strikeout performance by starter Emerson Hancock (7 IP, 7 H, 1 ER, 0 BB). Despite losing lost 2 straight games, the Mariners are 6-3 in their last 9.

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Royals at Mariners projected starters

LHP Kris Bubic vs. RHP Luis Castillo

Bubic (2-1, 3.74 ERA) makes his seventh start. He has a 1.19 WHIP, 4.5 BB/9 and 9.4 K/9 in 33 2/3 innings.

Last start: No-decision, 5 IP, 1 ER, 4 H, 4 BB, 6 K in 4-1 10-inning road loss to the A’s Tuesday
Career vs. Mariners: 1-0, 7.27 ERA (17 1/3 IP, 14 ER), 2.08 WHIP, 7.8 K/9 in 4 starts
2026 road splits: 0-0, 5.59 ERA (9 2/3 IP, 6 ER), 1.76 WHIP, 8.4 K/9 in 2 starts

Castillo (0-2, 6.35 ERA) makes his seventh start. He has a 1.73 WHIP, 3.5 BB/9 and 8.3 K/9 in 28 1/3 innings.

Last start: Loss, 5 IP, 7 ER, 7 H, 2 BB, 3 K in 11-4 road loss to the Minnesota Twins Monday
Career vs. Royals: 3-2, 3.47 ERA (46 2/3 IP, 18 ER), 1.11 WHIP, 6.8 K/9 in 8 starts
2026 home splits: 0-0, 5.65 ERA (14 1/3 IP, 9 ER), 1.61 WHIP, 10.0 K/9 in 3 starts

Royals at Mariners odds

Provided by BetMGM Sportsbook; access USA TODAY Sports Scores and Sports Betting Odds hub for a full list. Lines last updated at 11:19 a.m. ET.

Moneyline (ML): Royals +105 (bet $100 to win $105) | Mariners -125 (bet $125 to win $100)
Run line (RL)/Against the spread (ATS): Royals -1.5 (+170) | Mariners +1.5 (-210)
Over/Under (O/U): 8 (O: -102 | U: -118)

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Royals at Mariners picks and predictions

Prediction

Mariners 6, Royals 5

The Royals have have just 1 series sweep this season, and are looking for their first sweep of a team on the road. The Mariners have been swept twice this season, but not at home.

The Mariners are 6-3 in their last 9 games. The Royals are 4-12 on the road while Seattle is 10-8 at home.

BET MARINERS (-125).

Per Teamrankings.com, this is only the fourth time the Mariners are run-line underdogs. They are 1-3 ATS in those games with the lone win being outright as well.

The Royals are 2-6 ATS in their last 8 games as favorites, with 5 of those ATS losses being straight-up defeats.

But the better value for the Mariners is not betting them to cover. It is betting them to win outright.

PASS.

Three of Castillo’s last 5 starts have surpassed 8 total runs. Six of Seattle’s last 9 games have had at least 8 total runs.

Five of the Royals’ last 8 losses have had at least 8 total runs.