2025 National Bank Open – Men's singles

Ben Shelton defeated Karen Khachanov in the final, 6–7^(5–7), 6–4, 7–6^(7–3) to win the men's singles tennis title at the 2025 Canadian Open. It was his first ATP Masters 1000 title and third career ATP Tour title. Shelton was the youngest American man to win a Masters title since Andy Roddick at the 2004 Miami Open.

Alexei Popyrin was the defending champion, but lost in the quarterfinals to Alexander Zverev.

By reaching his first ATP 1000 final since the 2018 Paris Masters, Khachanov recorded the longest gap between successive ATP 1000 finals appearances, at 6 years and 9 months. With his third-round win, Zverev became the first man born in the 1990s to win 500 ATP Tour level main-draw singles matches, and the fifth active player to do so. Taylor Fritz became the first American man to reach the quarterfinals at all nine ATP 1000 tournaments.

This event marked the final professional appearance of former Davis Cup and Wimbledon doubles champion, Vasek Pospisil. He lost in the first round to Facundo Bagnis.