Background <p>While existing research has established associations among growth mindset, grit, learning engagement, and psychological well-being, the underlying mechanisms—specifically, whether grit and learning engagement serve as parallel mediators in the relationship between growth mindset and psychological well-being—remain underexplored.</p> Methods <p>This cross-sectional study investigated the relationship between growth mindset and adolescent psychological well-being, focusing on the potential parallel mediating roles of grit and learning engagement. In February 2025, 1142 adolescents from Shandong and Jiangsu provinces completed questionnaires assessing these constructs. Data were analyzed using structural equation modeling (SEM) with AMOS 24.0 and SPSS 24.0.</p> Results <p>(1) Growth mindset was significantly and positively associated with psychological well-being; (2) Grit mediated the relationship between growth mindset and psychological well-being; (3) Learning engagement mediated this relationship between growth mindset and psychological well-being.</p> Conclusion <p>These findings provide a novel theoretical perspective for understanding the determinants of adolescents’ psychological well-being. Additionally, they offer important implications for educational practice: targeted interventions (e.g., growth mindset training, grit cultivation, and learning engagement) are feasible approaches to improving adolescents’ psychological well-being.</p>