This study was designed to examine the roles of neighborhood social cohesion and parenting stress in influencing maternal mental health outcomes among primarily low‐income, unmarried, urban mothers. Structural equation modeling was conducted using cross‐sectional Fragile Families and Child Wellbeing Study data (N = 3,876), to test the hypotheses that neighborhood social cohesion would be associated with depression and anxiety among mothers with children aged 3 years and that this relationship would be mediated by parenting stress. The mediation model demonstrated good fit, χ2(796) = 3169.07, p < .001; comparative fit index = 0.96; root mean square error of approximation = 0.028 [90% confidence interval [0.027, 0.029]. Parenting stress partially mediated the effect of social cohesion on maternal depression (indirect effect: −0.04, p < 0.001) and anxiety (indirect effect: −0.05, p < 0.001); higher reported neighborhood social cohesion was associated with lower parenting stress, which was associated with a decreased likelihood of maternal anxiety and depression. Efforts to bolster neighborhood social cohesion may improve maternal mental health outcomes by reducing parenting stress.