Defending champion Carlos Alcaraz[1] defeated Jan-Lennard Struff in the final, 6–4, 3–6, 6–3 to win the men's singles tennis title at the 2023 Madrid Open.

[2] This was the first edition in the tournament's 21-year history to not feature Roger Federer, Rafael Nadal, or Novak Djokovic (collectively known as the Big Three) in the main draw.

[3] Zhang Zhizhen became the first Chinese tennis player to reach the singles quarterfinals of an ATP Masters 1000 event.

[5] The semifinal encounter between Karatsev and Struff was a rematch of their meeting in the qualifying rounds of the tournament, which Karatsev had won; Struff, who advanced to the main draw as a lucky loser after withdrawals, won their semifinal rematch.

† The player did not qualify for the main draw in 2022, but is defending points from Estoril, Munich, or Mauthausen (ATP Challenger).