Aim: This systematic review was designed to compare the clinical effectiveness of high-viscosity glass ionomer cement (HVGIC) restorations to direct composite resin (CR) restorations in single- or multisurface cavities in primary teeth. Background: Restorative procedures are typically used to treat caries in primary teeth. Due to their improved preservation of the natural tooth structure and their adhesion to the remaining tooth structure, CR and GIC have drawn attention as the preferred restorative materials. In the literature, over the past 20 years, the term HVGIC has developed. Compared to C-GICs, HVGICs appear to have a higher survival rate. However, isolated studies provide contradictory findings regarding the durability of restorations in primary teeth. Materials and methods: Major electronic databases were thoroughly searched to find publications from the years 2000 to 2021. Studies included were randomized and nonrandomized clinical trials on children aged 3–13 years, in which restoration of primary teeth using HVGIC and CR was performed. Results: This systematic review includes four studies [three randomized controlled trials (RCTs) and one nonrandomized controlled trial]. No statistically significant difference between these materials was seen in any of the included studies. Conclusion: This systematic review of findings supports the assertion that both HVGIC and CR restorations deliver satisfactory outcomes in terms of clinical efficacy and overall survivability. It was found that, for both materials, class I restorations had statistically higher survival rates than class II restorations. Long-term studies are essential to evaluate the clinical efficacy of both restorations. Clinical significance: This systematic review outlines the application of HVGIC and CR as restorative materials for pediatric dentists to use in their everyday dental practices.