While previous studies have established the importance of teacher support and grit in academic success, their combined influence on psychological wellbeing with gender as a moderator remains understudied. Using structural equation modelling (SEM) and mediation moderation analyses, this research analysed quantitative data obtained from various validated questionnaires administered to a sample of 355 Iranian undergraduate, postgraduate and doctoral English majors. Findings revealed that teacher support directly enhanced psychological wellbeing, while second language (L2) grit served as a significant mediator. The results also showed some gender difference in the direct and indirect effects of the examined variables. These findings highlight the need for pedagogical strategies guided by educational psychology to foster teacher support for greater academic achievement and learners' success in higher education settings. The study has implications for Continuing Professional Development (CPD) programmes in higher education to promote more gender-sensitive supportive learning environments that prioritise wellbeing. Further, it can encourage policymakers to adopt comprehensive strategies for implementing a research-based educational psychology approach in higher education.