This quantitative study investigated the influence of sports participation on the mental toughness of first-class cadets at the Philippine Military Academy (PMA). The research aimed to determine the extent to which engagement in sports contributes to psychological resilience, discipline, and performance under pressure among cadets in a highly demanding military training environment. Using a correlational research design, data were collected through a standardized questionnaire measuring sports participation and mental toughness, and identified the relationship of the two identified variables. The study involved first-class cadets enrolled during the academic year of 2025–2026, with ethical considerations such as informed consent, confidentiality, and voluntary participation strictly observed. Results revealed that cadets exhibited a high level of sports participation (GWM = 3.69), emphasizing camaraderie, physical endurance, and motivation, and a very high level of mental toughness (GWM = 3.80), characterized by perseverance, confidence, adaptability, and emotional control. A Pearson’s correlation analysis indicated a very strong direct relationship between sports participation and mental toughness (r = 0.89, p < 0.05), with 79% of the variance in mental toughness explained by sports participation. These findings highlight the critical role of structured sports activities in developing the psychological competencies necessary for effective leadership and operational success in military training. The study suggests that integrating more structured and competitive sports programs into the PMA curriculum could further enhance cadets’ mental toughness, resilience, and stress management abilities. Future research may explore additional factors influencing mental toughness, including coaching styles, leadership exposure, and personal characteristics, to provide a more comprehensive understanding of cadet development.