Maternal depressive symptoms are a major public health concern in low- and middle-income countries (LMICs), yet evidence on their relationship with early childhood development (ECD) remains mixed. This study examined the association between maternal depressive symptoms and ECD outcomes during infancy and toddlerhood, and whether household composition moderated these associations. Additionally, we examined whether child stimulation activities were associated with ECD outcomes across both timepoints. We analysed data from 769 mother-child dyads drawn from a cluster-randomised controlled trial conducted in the Cajamarca region of Peru. Maternal depressive symptoms were assessed during infancy (approximately 5 months) using the DASS-21 depression subscale. Child development was assessed during infancy (mean age 5.2 months) using the CREDI and during toddlerhood (mean age 28.7 months) using the GSED Long Form. Associations were examined using linear regression models, adjusting for demographic, household, social, and caregiving covariates. Effect modification by number of siblings under 6 years and number of adults in the household was assessed. Approximately one in six mothers (17.4%) reported any depressive symptoms. Maternal depressive symptoms were neither associated with child development outcomes in infancy (adjusted {beta} = 0.01, 95% CI [-0.01, 0.01]) nor in toddlerhood (adjusted {beta} = -0.01, 95% CI [-0.07, 0.05]). No significant moderation was observed for either household composition variable. Among the covariates examined in the adjusted models, child stimulation activities showed the strongest independent association with child development at both timepoints, regardless of maternal depressive symptom status. We found no evidence that maternal depressive symptoms were associated with child development during infancy or toddlerhood, and household composition did not moderate these associations. These findings suggest that the relationship between maternal depressive symptoms and early child development may be more complex than previously assumed in this rural Andean context. However, the absence of an association in this study should not be interpreted as evidence that maternal depressive symptoms are unimportant, as previous research has documented important effects on maternal wellbeing, family functioning, and child outcomes.