Parental phubbing behavior is a significant predictor of adolescent smartphone dependence. However, previous research has mainly focused on the child and adolescent’s perspective, overlooking potential differences in how parents and their children perceive parental phubbing. Therefore, this study investigates whether disparities exist in how parents and adolescents perceive parental phubbing and how these perceptual differences impact adolescent smartphone dependence. We also explore the role of the parent–child relationship in this context. In this study, 728 families from a middle school in Wuhan were selected and surveys were administered to both children and parents. The findings are as follows: (1) Significant perceptual differences were found between parents and adolescents regarding parental phubbing. (2) These perceptual discrepancies positively predict adolescent smartphone dependence and negatively impact parent–child relationships. Additionally, parent–child relationships have a negative influence on adolescent smartphone dependence. (3) The parent–child relationship serves as a mediator between perceptual differences in parental phubbing behavior and adolescent smartphone dependence. In summary, this research highlights the importance of considering both parent and adolescent perspectives on parental phubbing and emphasizes the role of the parent–child relationship in influencing adolescent smartphone dependence.