Aim <p>ChatGPT is increasingly used as an informal tool for mental health support, despite limited empirical evidence.</p> Subject and methods <p>This mixed-methods study explored ChatGPT use for mental-health purposes, examining perceived benefits and barriers, and age-related differences. In phase 1, semi-structured interviews with 12 university students informed the development of a 19-item online survey, administered to Catalan-speaking individuals aged 16 and older.</p> Results <p>Interviews revealed diverse usage patterns. Between January and June 2025, 500 participants (age range 16–90&#xa0;years, M 41.15, SD 17.7) completed the survey. Overall, 74.6% (<i>n</i> = 373) reported using ChatGPT, but only 17.2% (<i>n</i> = 86) had consulted it for mental health support and typically did so infrequently (≤ monthly). Most queries concerned stress or anxiety (64%) and interpersonal problems (53.5%). Main motivations were access to coping strategies (73.3%), obtaining alternative perspectives (61.6%) and organising thoughts (53.5%). Among those who consulted ChatGPT for mental health reasons, 55.8% rated its helpfulness as moderate to high. ChatGPT use decreased significantly with age, from 39.5% among adolescents to 3.6% among adults aged 50–64&#xa0;years (χ²₍₅₎ = 21.4, <i>p</i> &lt; 0.001).</p> Conclusion <p>ChatGPT may serve as an easily accessible, complementary resource for everyday mental-health concerns, particularly for younger users. Initiatives to foster informed and responsible use may be especially relevant for adolescents and young adults. However, given the exploratory nature of this study, it is still premature to derive any public-health recommendation. More research is needed to examine the efficacy, safety and real-world impact of using ChatGPT for mental-health purposes.</p>