The aim of this study was to analyse the differentiated role played by academic self-concept on teacher identity, taking into account the mediating role of teacher efficacy and the gender of the pre-service physical-education teachers. In this cross-sectional study, 478 master’s degree students in Secondary Education Teacher Training participated (Mean = 27.09; SD = 6.32; 54.8% male, 44.8% female, 0.4% other). The following scales were used: academic self-concept, teaching identity, and teacher self-efficacy. After finding significant differences in academic effort, a structural equation analysis (SEM) with the multigroup option was conducted to answer the research objective. The results revealed that the women had significantly higher mean academic effort values than the men. In addition, the SEM, which showed excellent fit indices, revealed that, for the men, teacher efficacy acted as a mediating variable between academic confidence and teacher identity. In contrast, for the women, teacher efficacy acted as a mediator between academic effort and teacher identity. However, academic effort also acted as a direct predictor of teacher identity in male pre-service teachers. As a main conclusion, it can be said that the findings highlight the importance of academic self-concept in undertaking the master’s degree by increasing teacher identity through the teaching efficacy of pre-service teacher educators.