The present study aims to examine and compare, in both mobile phone addicts (MPAs) and possible-MPAs, (1) the direct effect of mobile phone addiction (MPA) levels on adolescent depressive symptoms, and (2) the indirect effect of MPA levels on depressive symptoms as mediated by parent-adolescent relationships. We recruited 1766 Chinese adolescents (53.2% male; M= 13.30, SD = 2.00, range from 10 to 18 years) from Shenzhen Shuijing Primary School, Shenzhen Longcheng Middle School, and High School of Shenzhen Overseas Chinese Town in China. The participants completed a questionnaire survey that measured MPA levels, parent-adolescent relationships, and depressive symptoms. The results showed that (1) The direct effect of MPA on adolescent depressive symptoms was stronger than that of possible MPA; (2) the indirect effect of MPA on depressive symptoms through parent-adolescent relationships was stronger than that of possible MPA. This study expanded the interdependent relationship between Internet addiction and depression by illustrating the mediating mechanism of parent-adolescent relationships in the link between different levels of MPA and adolescent depressive symptoms, having made an important contribution to the development of family-based prevention and intervention strategies for adolescent depressive symptoms.