Child undernutrition, particularly stunting, wasting and micronutrient deficiencies, remains a major health concern in rural communities in Vietnam. While literature suggests leveraging agriculture to improve child nutrition via agricultural diversification, market engagement, and women empowerment, very few studies have explored how smallholder vegetable production can influence child nutrition outcomes. The present paper tries to fill this gap using a nutrition-centred approach that examines the impacts of vegetable production diversity, market access, and market participation at the household level. We use a cross-sectional household dataset that we collected in 2016 in Northwest Vietnam covering 234 children aged 6 to 60 months. We estimate several regression models using three-stage least squares (3SLS), ordinary least squares (OLS), logistic regression, and seemingly unrelated regression (SUR), in their most appropriate settings and in a comparative manner to explain variations in several nutrition outcome measures, including height-for-age (HAZ), weight-for-height (WHZ), and weight-for-age (WAZ) Z-scores, as well as three other measures (stunting, wasting, and underweight). Our results suggest that smallholder vegetable production has a significant indirect effect on child nutrition via market participation. Market participation is an important factor in improving girls’ HAZ and WHZ, and in reducing the probabilities of boys being stunted and underweight. It is implied that additional income from selling vegetables allows households to purchase nutritious food, which is likely to have a positive impact on child nutrition outcomes.