Purpose <p>To evaluate whether a growth mindset improves the health-related quality of life (HRQoL) in adolescent idiopathic scoliosis (AIS) patients compared to a fixed mindset.</p> Methods <p>AIS patients who were under observation or treated with a brace for at least 3&#xa0;months were included in this cross-sectional study. HRQoL was measured using the Scoliosis Research Society-22 revised (SRS-22r) and the European Quality of Life Five Dimension Three-Level (EQ-5D-3L) questionnaires. Mindset was assessed using the Health Mindset Scale questionnaire. Statistical analyses were performed using Pearson correlation coefficients and independent samples <i>t</i>-tests.</p> Results <p>A total of 355 patients met the inclusion criteria. Of which, 227 were under observation and 128 were under brace treatment. Both treatment groups had similar distributions of mindset groups (<i>p</i> = 0.093) and Health Mindset Scale scores (<i>p</i> = 0.092). In the observation group, a growth mindset was significantly correlated (r = −&#xa0;0.147, <i>p</i> = 0.026) and associated (<i>p</i> = 0.004) with better Usual Activities. In the brace group, a growth mindset was significantly associated with greater Function (<i>p</i> = 0.041).</p> Conclusion <p>AIS patients with a growth mindset reported better HRQoL outcomes in specific domains. Those under observation reported better Usual Activities, while those under brace treatment reported greater Function. Previous research has demonstrated that interventions to promote a growth mindset are possible and beneficial. Since improving the quality of life is the main goal of scoliosis treatments, supplementary therapy to foster a growth mindset in patients could enhance their overall quality of living beyond the direct effects of physical treatments.</p> Clinical trial number <p>Not applicable.</p>