The number of people in low- and middle-income countries who suffer from depression is increasing, and a significant proportion of people in these countries live in poverty. We estimated the effect of living in multidimensional poverty on experiencing symptoms associated with major depression using the 2018 Peruvian Demographic and Health Survey. We used an instrumental variables approach to overcome the potential endogeneity bias caused by the simultaneous relationship between multidimensional poverty and depression. We found that living in multidimensional poverty significantly increases depression symptom severity. This has urgent policy implications for low- and middle-income countries with limited provision of mental health services.