Background aims Micronutrients are essential for brain development with deficiencies in specific nutrients linked to impaired cognitive function. Interventions are shown to be beneficial to children's mental development, particularly in subjects who were micronutrient-deficient at baseline but results on healthy subjects remain inconsistent. This systematic review evaluated the effect of micronutrient inventions on different cognitive domains. Studies conducted in both developing and developed countries, and trials that investigate the effect of both single and multiple micronutrient intervention were reviewed. Methods Systematic searches of Medline, CINAHL Plus and Academic Search database were undertaken to identify trials published after year 2000. Randomized controlled trials (RCTs) that evaluate the effect of micronutrients on cognitive performance or academic performance among children aged 4–18 years were included. Results 19 trials were identified from 18 articles. The major cognitive outcomes assessed included fluid intelligence, crystallized intelligence, short-term memory, long-term memory, cognitive processing speed, attention and concentration, and school performance. Eight of ten trials assessing fluid intelligence reported significant positive effects of micronutrient supplementation among micronutrient-deficient children, especially those who were iron-deficient or iodine-deficient at baseline. The effects of micronutrient interventions on other domains were inconsistent. Conclusion Improvement in fluid intelligence among micronutrient-deficient children was consistently reported. Further research is needed to provide more definite evidence on the beneficial effects of micronutrient inventions on other cognitive domains and the effects in healthy subjects.