Nigeria has high rates of stunting and wasting among primary school children, highlighting the need for effective nutrition interventions. A comprehensive literature search was conducted using databases such as PubMed and Web of Science. Studies were included based on predefined criteria, including sample size, intervention type, and outcome measures. Data were analysed using Comprehensive Meta-Analysis software to calculate weighted mean effects with corresponding confidence intervals. The analysis included 25 studies involving over 10,000 children across Nigeria. Overall, school-based nutrition interventions showed a significant positive effect on height-for-age (HFA) and weight-for-height (WHZ), with an estimated average increase of 3% in HFA and 4% in WHZ. School-based nutrition programmes appear to be effective in improving growth metrics among Nigerian primary school children, though there is variability by intervention type and geographic region. Future research should focus on the specific components of interventions that are most effective, as well as long-term sustainability strategies. Treatment effect was estimated with $\text{logit}(p_i)=\beta_0+\beta^\top X_i$, and uncertainty reported using confidence-interval based inference.