Mariners vs Reds Prediction, Odds, Moneyline, Spread & Over/Under for July 21

Odds updated as of 9:13 a.m.

The Tuesday schedule in MLB includes a matchup between the Seattle Mariners and the Cincinnati Reds.

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

Mariners vs Reds Game Info

• Seattle Mariners (51-50) vs. Cincinnati Reds (45-54)
• Date: Tuesday, July 21, 2026
• Time: 9:40 p.m. ET
• Venue: T-Mobile Park -- Seattle, Washington
• Coverage: Mariners.TV and Reds.TV

Mariners vs Reds Odds & Moneyline

• All MLB odds, betting lines and prop bets are available on FanDuel Sportsbook.
• Moneyline: SEA: (-112) | CIN: (-104)
• Spread: SEA: +1.5 (-192) | CIN: -1.5 (+158)
• Total: 7.5 -- Over: (-105) | Under: (-115)

Mariners vs Reds Probable Starting Pitchers

Probable Pitchers: Luis Castillo (Mariners) - 3-8, 4.93 ERA vs Chase Burns (Reds) - 11-1, 2.54 ERA

The probable pitchers are Luis Castillo (3-8) for the Mariners and Chase Burns (11-1) for the Reds. Castillo's team is 4-11-0 against the spread in his starts this season. Castillo's team has a record of 3-6 this season when he starts and they are the favorite on the moneyline. When Burns starts, the Reds are 14-4-0 against the spread. The Reds have been the moneyline underdog in five of Burns' starts this season, and they went 4-1 in those matchups.

Mariners vs Reds Prediction & Pick

All MLB win probability predictions and picks are according to numberFire.
Prediction: Mariners win (61%)

Mariners vs Reds Moneyline

• Seattle is the favorite, -112 on the moneyline, while Cincinnati is a -104 underdog on the road.

Mariners vs Reds Spread

• The Reds are 1.5-run favorites against the spread for this matchup with the Mariners. The Reds are +158 to cover, while the Mariners are -192 to cover as a 1.5-run underdog on the runline.

Mariners vs Reds Over/Under

• A combined run total of 7.5 has been set for Mariners-Reds on July 21, with the over at -105 and the under at -115.

Bet on Seattle Mariners vs. Cincinnati Reds on FanDuel today!

Mariners vs Reds Betting Trends

• The Mariners have won in 46, or 54.1%, of the 85 contests they have been named as odds-on favorites in this year.
• Seattle has a record of 46-38 in contests when sportsbooks favor them by -112 or more on the moneyline.
• The Mariners' games have gone over the total in 48 of their 100 opportunities.
• The Mariners have an against the spread record of 37-63-0 in 100 games with a line this season.
• The Reds have won 44.6% of the games this season they were the underdog on the moneyline (29-36).
• Cincinnati has a record of 24-35 when it has played as a moneyline underdog with odds of -104 or longer (40.7%).
• The Reds have had an over/under set by bookmakers 97 times, and have combined with opponents to go over the total in 55 of those games (55-41-1).
• The Reds have a 52-45-0 record against the spread this season (covering 53.6% of the time).

Mariners Player Leaders

• Randy Arozarena leads Seattle with 96 hits and an OBP of .381, plus a team-best slugging percentage of .450. He's batting .284.
• Among qualifying hitters in MLB, his batting average ranks 26th, his on-base percentage ranks 13th, and he is 58th in slugging.
• Arozarena has hit safely in two games in a row. During his last five outings he is batting .222 with a home run, a walk and three RBIs.
• Josh Naylor is hitting .253 with 12 doubles, eight home runs and 31 walks, while slugging .351 with an on-base percentage of .317.
• Among all qualifying players, he ranks 79th in batting average, 95th in on-base percentage and 134th in slugging percentage.
• Naylor has picked up at least one hit in two straight games. During his last five outings he is batting .278 with two walks and an RBI.
• Cole Young has collected 92 base hits, an OBP of .314 and a slugging percentage of .406 this season.
• Julio Rodriguez is batting .256 with a .320 OBP and 42 RBI for Seattle this season.
• Rodriguez has safely hit in two games in a row. During his last five outings he is hitting .313 with two walks and two RBIs.

Reds Player Leaders

• Sal Stewart has a .470 slugging percentage, which paces the Reds. He's batting .251 with an on-base percentage of .331.
• He ranks 81st in batting average, 76th in on-base percentage and 43rd in slugging percentage among all qualified hitters in the big leagues.
• Elly De La Cruz's 89 hits and .352 on-base percentage both pace his team. He has a batting average of .279 while slugging .502.
• Including all qualifying hitters, he ranks 37th in batting average, 45th in on-base percentage and 21st in slugging percentage.
• Spencer Steer is batting .245 with 14 doubles, 16 home runs and 34 walks.
• JJ Bleday has 11 doubles, a triple, 16 home runs and 41 walks while hitting .239.

Mariners vs Reds Head to Head

• 7/20/2026: 8-0 SEA (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -146, Underdog Moneyline: +124)
• 4/17/2025: 11-7 SEA (Favorite: Reds, Spread: -1.5, Total: 8.5, Favorite Moneyline: -130, Underdog Moneyline: +110)
• 4/16/2025: 5-3 SEA (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -112, Underdog Moneyline: -104)
• 4/15/2025: 8-4 CIN (Favorite: Mariners, Spread: -1.5, Total: 8.5, Favorite Moneyline: -112, Underdog Moneyline: -104)
• 4/17/2024: 5-1 SEA (Favorite: Mariners, Spread: -1.5, Total: 7.5, Favorite Moneyline: -130, Underdog Moneyline: +110)
• 4/16/2024: 3-1 SEA (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -142, Underdog Moneyline: +120)
• 4/15/2024: 9-3 SEA (Favorite: Mariners, Spread: -1.5, Total: 7, Favorite Moneyline: -154, Underdog Moneyline: +130)
• 9/6/2023: 8-4 SEA (Favorite: Mariners, Spread: -1.5, Total: 9.5, Favorite Moneyline: -174, Underdog Moneyline: +146)
• 9/5/2023: 7-6 CIN (Favorite: Mariners, Spread: -1.5, Total: 10.5, Favorite Moneyline: -152, Underdog Moneyline: +128)
• 9/4/2023: 6-3 CIN (Favorite: Mariners, Spread: -1.5, Total: 10.5, Favorite Moneyline: -158, Underdog Moneyline: +134)

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