The growing integration of digital technologies into adolescents’ everyday lives has increased the need to examine online-use patterns, family relationships, and psychological functioning simultaneously. This study examined the associations of cyberspace dependency and perceived supportive parenting with psychological distress among upper-secondary school students in Talesh County, Iran. The conceptual framework distinguishes daily time spent in cyberspace from cyberspace dependency, understood as a pattern of problematic and poorly controlled Internet use, while considering perceived parenting alongside adolescents’ digital experiences. Using a quantitative approach, the study employed a cross-sectional survey design. The statistical population comprised upper-secondary school students in Talesh County during the 2024–2025 academic year, from whom 300 students were selected through stratified random sampling. Data were collected using the Compulsive Internet Use Scale, the General Health Questionnaire, and the Perceptions of Parents Questionnaire, and were analyzed through Pearson correlation, multivariate analysis of variance, and multiple linear regression. Mean scores for somatic symptoms, anxiety and insomnia, social dysfunction, and depressive symptoms were higher among groups reporting longer daily cyberspace use, with significant overall differences across all four dimensions. In the regression model, cyberspace dependency was positively and significantly associated with psychological distress, whereas perceived supportive parenting showed a significant inverse association. Together, these variables explained 54.9 percent of the variance in psychological distress. The findings indicate that understanding adolescents’ psychological functioning requires simultaneous attention to daily use, cyberspace dependency, and perceived family support; however, the cross-sectional design does not permit causal inference.