Background: Being treated in an emergency room (ER) could be a stressful experience and trigger anxiety in children. Virtual reality (VR) is a technology-based distraction technique that can be used for school-age children. Objective: In this study, we aimed to identify the effect of using VR in reducing anxiety in school-age children in the ER and identify the relationship between caregivers’ and school-age children’s anxiety. Methods: This study employed a true experimental design using a post-test-only control group involving 66 children aged 6‐12 years, randomly selected according to the inclusion and exclusion criteria. The intervention group, consisting of 33 children, received VR intervention, and the control group, consisting of 33 children, received standard care. Three respondents dropped out. Data analysis employed descriptive statistics, independent t tests, one-way ANOVA, and Pearson correlation analysis. Results: Most respondents were boys (39/66, 61.9%), accompanied by their mother (34/63, 54%), and had prior experience admitted to the ER (31/63, 49.2%). The anxiety in school-age children in the intervention group (mean 17.71, SD 3.013) was lower than that in the control group (mean 22.31, SD 3.167). There was a significant difference in the anxiety mean scores between the intervention group and the control group (t(61)=−5.907, P<.001). The mean (SD) of the caregivers’ anxiety in the intervention and control groups were 46.06 (9.413) and 54.44 (9.112), respectively. There was a moderate relationship between caregivers’ and school-age children’s anxiety (r=.532, P<.001). Conclusions: This study has proven that VR can reduce school-age children’s anxiety. © Enjelita Karujan, Dessie Wanda, Efa Apriyanti.