Although excessive use of social networking site (SNS) is related to undesired effects on healthy individual's psychological well-being, there is a huge gap in studies performed with individuals who suffer from various mental disorders. The main goal of this study is to examine the association between problematic utilization of SNSs and depressive symptoms across patients diagnosed with major depressive disorder (MDD). 111 patients diagnosed with MDD (diagnoses confirmed via the Structured Clinical Interview for DSM-5-Clinician Version (SCID-5/CV)) and 108 healthy controls (HCs) were recruited for the study. Montgomery-Asberg Depression Rating Scale (MADRS) and Bergen Social Media Addiction Scale (BSMAS) were administered by both MDD and HC groups. Group comparisons were estimated with multivariate analysis of covariance (MANCOVA) analyses. To identify the relationship between SNS addiction and depressive symptoms, the Pearson correlations were performed, and finally, we computed the multiple linear regression analyses to determine whether SNS addiction predicts depressive symptoms. The results revealed that MDD group is more addicted to SNS relative to HC. In addition, depressive symptoms were significantly predicted by 'relapse' subdimension and the overall score of SNS addiction in the MDD group. Our study illustrated the detrimental effects of excessive SNSs usage on depressive symptoms in MDD particularly for the individuals in 'relapse' state of SNS addiction. The mental health workers should consider the usage patterns of SNSs in patients diagnosed with MDD during their clinical observation and management.