Objective: This study aimed to examine the moderating effect of elementary school students’ perception of open communication with their parents in relationship to smartphone dependency and school adjustment. Methods: Participants included 300 fifth and sixth graders attending P and A elementary schools in Gyeonggi Province. Descriptive analysis, correlation analysis, and hierarchical regression analysis were performed to analyze data. The level of significance was set at p < .05 for all analyses. Results: The results of the present study are as follows: First, male students showed higher levels of smartphone dependency than female students, and students’ smartphone dependency increased according to age. The students’ smartphone dependency was negatively associated with their school adjustment and their perception of open communication with their parents. Second, the students’ perception of open communication with their fathers was found to moderate the relationship between smartphone dependency and school adjustment. Conclusion/Implications: These findings indicate that open communication between parents and their elementary school-aged children can buffer the adverse effects of smartphone dependency on school adjustment. This study provides implications for parent education and counseling to improve parent-child communication and subsequently build strong, positive family relationships.