Purpose <p>University student-athletes need sufficient nutrition from a healthy diet to maintain performance and improve competitive ability. This study aimed to identify the eating behaviors supporting healthy diets among male university student-athletes in Japan.</p> Methods <p>The exploratory qualitative study using semi-structured interviews was conducted in January 2023 to determine the eating behaviors of four participants selected according to the inclusion criteria. Based on the results of the qualitative study, the quantitative questionnaire survey was conducted among 572 male university student-athletes from July to September 2023. Associations between the frequency of daily intake of staple dishes, main dishes, side dishes, dairy products, and fruits and eating behaviors extracted from qualitative research were examined using chi-square tests and multinomial logistic regression analyses.</p> Results <p>The qualitative study identified six eating behaviors that support healthy diets: choosing what to eat nutritionally; eating an appropriate amount of food; checking nutrition information labels; having regular meals; adjusting what to eat according to training and competitions; and adjusting when to eat according to training and competitions. The quantitative survey showed that those who ate a moderately balanced diet only engaged in three of the six eating behaviors, while those who ate a healthy diet engaged in all six behaviors.</p> Conclusion <p>Six eating behaviors associated with healthier dietary quality among male university student-athletes were identified. Nutrition education programs should promote these specific eating behaviors to support healthy dietary practices.</p>