Objectives: Caring for adolescents with developmental disabilities (DD) is stressful and challenging, and mothers usually provide care for these children in Korea. This study aimed to identify factors influencing quality of life (QoL) in mothers of adolescents with DD.Methods: A predictive design was used. Data were collected from a web-based survey administered to a convenience sample of 154 mothers of adolescents with DD from October to November 2020. Data were analyzed using the t-test, analysis of variance, Pearson correlation coefficients, and multiple regression.Results: Perceived health, depression, and family strength were significantly correlated with QoL. Multiple regression showed that family strength, perceived health, depression, and monthly household income influenced the participants’ QoL, and these factors accounted for 69.2% of variance in QoL. Family strength was the factor most strongly affecting QoL (β=0.39).Conclusion: The study results indicate that health professionals and policy-makers need to pay attention to the overall QoL and physical and psychological health of mothers of adolescents with DD. Since our findings raise the importance of family strength in the QoL of this population, programs to improve family strength need to be implemented and strengthened. Interventions to improve perceived health and decrease depression should be applied, and knowledge on adolescent characteristics and changes should be delivered to caregivers when providing education and consultations. The findings will be helpful for developing educational and counseling programs for this population.