Background <p>This meta-analysis assessed the impact of internet-based interventions on adolescents’ quality of life (QoL).</p> Methods <p>A systematic electronic database searching was conducted through November 12, 2024, to identify pertinent studies. Randomized controlled trials evaluating internet-based interventions including cognitive-behavioral therapy, mindfulness training, and online peer support in adolescents aged 10–19 years were included. Studies were required to measure QoL using validated instruments with CHU9D, PedsQL, Brunnsviken Brief Quality of Life scale, or Health-Related Quality of Life scales and compare interventions against standard care, face-to-face therapy, or no treatment. Studies with participants outside the adolescent age range or without QoL outcomes were excluded. Effect sizes were quantified using standardized mean difference and standard error. Five studies were included, with 156 participants in the intervention group and 167 in the usual care group.</p> Results <p>Five studies involving 323 participants were included. Overall, internet-based interventions showed a small and non-significant effect on adolescents’ quality of life. Subgroup analyses suggested that shorter interventions may be associated with modest improvements, whereas longer interventions showed inconsistent or potentially unfavorable effects. However, substantial heterogeneity was observed across studies, reflecting differences in populations, intervention types, and outcome measures.</p> Conclusion <p>Internet-based interventions do not demonstrate a consistent overall benefit for adolescents’ quality of life. Given the considerable heterogeneity and limited number of studies, findings should be interpreted with caution. In clinical practice, careful consideration of intervention duration and developmental stage is recommended when implementing internet-based programs for adolescents.</p>