Economic evaluation is crucial for cost-effective resource allocation to improve child nutrition in low and middle-income countries (LMICs). However, the quality of published economic evaluations in these settings is not well understood. This systematic review aimed to assess the quality of existing economic evaluations of child nutrition interventions in LMICs and synthesize the study characteristics and economic evidence. We searched 9 electronic databases, including MEDLINE, with the following concepts: economic evaluation, children, nutrition, and LMICs. All types of interventions addressing malnutrition, including stunting, wasting, micronutrient deficiency, and overweight, were identified. We included economic evaluations that examined both costs and effects published in English peer-reviewed journals and used the Drummond checklist for quality appraisal. We present findings through a narrative synthesis. Sixty-nine studies with diverse settings, perspectives, time horizons, and outcome measures were included. Most studies used data from sub-Saharan Africa and South Asia and addressed undernutrition. The mortality rate, intervention effect, intervention coverage, cost, and discount rate were reported as predictors among studies that performed sensitivity analyses. Despite the heterogeneity of included studies and the possibility of publication bias, 81% of included studies concluded that nutrition interventions were cost-effective or cost-beneficial, mostly based on a country's cost-effectiveness thresholds. Regarding quality assessment, the studies published after 2016 met more criteria than studies published before 2016. Most studies had well-stated research questions, forms of economic evaluation, interventions, and conclusions. However, reporting the perspective of the analyses, justification of discount rates, and describing the role of funders and ethics approval were identified as areas needing improvement. The gaps in the quality of reporting could be improved by consolidated guidance on the publication of economic evaluations and the use of appropriate quality appraisal checklists. Strengthening the evidence base for child malnutrition across different regions is necessary to inform cost-effective investment in LMICs. Trial registration: PROSPERO CRD42020194445.