Background: Uncertainties and difficulties associated with the current treatment modalities for perinatal depression (PND) may cause some mothers to avoid treatment. Raising awareness about the effectiveness and safety of bright light therapy (BLT) may help to alleviate the challenges of PND. The main goal of this study was to evaluate the efficacy and safety of BLT versus placebo in PND.& nbsp;Method: A total of 30 women who were either pregnant or in first year postpartum and diagnosed with major depressive disorder were enrolled; 23 completed the study. Patients were randomly assigned to either the BLT (10,000 lux) or placebo (< 500 lux) group. BLT and placebo light were applied for 45 min in the morning every day for a 3-week period. The Montgomery-Asberg Depression Rating Scale (MADRS), Hamilton Depression Rating Scale (HAM-D), and Edinburgh Postnatal Depression Scale (EPDS) were administered weekly to evaluate response and remission rates and depression scores.& nbsp;Results: There was no significant difference between the two groups in terms of baseline depression scores. At the end of the study, the response rates assessed according to MADRS were 75% for BLT and 18.2% for placebo (p = .006), and remission rates were 41.7% vs. 0% (p = .016), respectively. There was no significant difference between the groups (p > .05) in terms of treatment-related side effects. The main limitation of this study is its small sample size, which limits the generalizability of the study's findings.& nbsp;Conclusion: The results indicate that BLT is more effective than placebo and is reliable in terms of side effects in PND patients. In order to expand the use of BLT in PND, new studies with larger sample sizes are needed.