Background: The aim of the present study is to estimate the prevalence of unintended pregnancy in fathers with children aged less than or equal to 36 months evaluate whether unintended pregnancy is associated with depression after controlling for covariates. Methods: We used data from the Brazilian National Health Survey (PNS) of 2019, a cross-sectional study that comprised a representative sample of residents in households in Brazil. For the analysis of this study, we selected 30,579 men (> 14 years old) who answered to the Selected Resident questionnaire of the reported having a biological child (son). Among these 4806 had a child with less than 4 years of age and were used in our analysis. Results: The prevalence of unintended pregnancy in this group of fathers with a child <= 3 years was 35.0 % (95 % CI 32.6-37.5). In the final adjusted model, variables associated with depression were: PHQ-9 total score (OR: 1.07, 95 % CI 1.03-1.11, p <= 0.001), a higher father's age (OR 1.01, 95 % CI 1.01-1.02), father's age at birth (OR: 0.92, 95 % CI 0.90-0.94), self-reported black (OR: 3.00, 95 % CI 1.94-4.66), brown (OR: 1.63, 95 % CI 1.25-2.13) or indigenous (OR: 95 % CI 0.07-0.69) skin color, lower per capita family income >1 to 2 MW (OR: 1.54, 95 % CI 1.01-2.35), 1 / 2 to 1 MW (OR: 2.22, 95 % CI 1.46-3.38) and up (OR: 1.76, 95 % CI 1.19-2.59) and not participating in the partner's prenatal appointments (OR: 2.04, 95 % CI 1.55-2.68). Discussion: In our study, the prevalence of unplanned pregnancy among fathers of child less than 4 years of age is high, and it is associated with depression. Black brown self-reported skin color, lower family income and higher father's age are associated with increased risk of unintended pregnancy.