The following are the seeded players. Seedings are based on ATP rankings as of 28 July 2025. Rankings and points before are as of 4 August 2025.
Due to a change in schedule this year, ATP ranking points from the 2024 National Bank Open held in Montreal and the 2024 Cincinnati Open will both be dropped at the end of the 2025 Cincinnati Open.[4] Accordingly, the points defending column in the table below reflects the relevant player's results from both Cincinnati and Montreal 2024, with the Cincinnati result listed first. Unless otherwise specified, any points deducted from Montreal will be replaced with the player's next best result (listed second under points earned). Note that this method of calculating ranking points for this year's tournament is different from the WTA's method.
† The player is only defending 2024 points from Cincinnati as his 2024 points from Montreal were replaced by a better result for purposes of his ranking as of 4 August 2025. ‡ The player is only defending 2024 points from Montreal as he either did not qualify for the 2024 tournament in Cincinnati, or his 2024 points from Cincinnati were replaced by a better result for purposes of his ranking as of 4 August 2025. § The player is defending 2024 points from neither Cincinnati nor Montreal. Instead, he is defending points from either his 19th best result or from an ATP Challenger Tour tournament (Cary).
‡ The player is only defending 2024 points from Montreal as his 2024 points from Cincinnati were replaced by a better result for purposes of his ranking as of 4 August 2025.
‡ – withdrew from entry list before qualifying began † – withdrew from entry list after qualifying began @ – withdrew from entry list using protected ranking and awarded wildcard § – withdrew from main draw