BACKGROUND: The effect of basal metabolic rate (BMR) on depression was unclear. This study investigated the potential role of BMR in the association of polycyclic aromatic hydrocarbons (PAHs) exposure and depression. METHODS: The study based on the National Health and Nutrition Examination Survey (NHANES). BMR was calculated using both the revised Harris-Benedict equation (BMR1) and the Mifflin-St Jeor equation (BMR2). Generalized linear and logistic regression models were applied to examine the associations between PAH metabolites, BMR, and depression. Weighted Quantile Sum (WQS) regression and Bayesian Kernel Machine Regression (BKMR) were utilized to analyze the combined effects of multiple PAH metabolites. Mediation analysis was conducted to explore the role of BMR. RESULTS: The study included 8323 participants. A 100 kcal/day increase in BMR1 and BMR2, the depression risk increased by 5 % (95%CI: 1.00, 1.10) and 7 % (95%CI: 1.02, 1.13), respectively. WQS model indicated that mixed PAH metabolites were negatively associated with BMR1 (β: -0.06, P = 0.020) and BMR2 (β: -0.06, P = 0.014). BKMR models showed that when all PAH metabolites were at P CONCLUSION: PAH exposure led to a reduction in BMR and contributed to depression at high levels of exposure. An increase in BMR mitigated the impact of PAH exposure on depression.