The present study investigates whether gender-related public self-consciousness moderates the relationship between students' gender and emotions in mixed-gender physical education classes. The Positive and Negative Affect Scales and the Gender-related Public Self-Consciousness Scale were administered to 380 middle-school students in South Korea. The preliminary analysis included a t-test and ANOVA. Subsequently, a hierarchical regression analysis was performed. The results showed that girls' gender-related public self-consciousness was significantly higher than that of boys. Further, gender-related public self-consciousness significantly moderated the relationship between gender and positive emotion, and while it moderated the relationship between gender and negative emotion, the effect was negligible. Gender-related public self-consciousness plays a role in mixed-gender physical education class. Thus, gender and gender-related public self-consciousness can help educators better understand students' emotions. These findings can inform guidelines for planning mixed-gender physical education course curricula.