ImportanceVaccination against COVID-19 is an effective method for individuals to reduce negative health outcomes. However, widespread COVID-19 vaccination among children has been challenging owing to parental hesitancy.ObjectiveTo examine parental decision-making in favor of the COVID-19 vaccine for their children and its association with the sufficiency and credibility of the information about the vaccine.Design, Setting, and ParticipantsThis cross-sectional survey study was conducted in South Korea from February 7 to 10, 2022, 7 weeks before initiation of the COVID-19 vaccine for children aged 5 to 11 years. Parents were included if they spoke Korean and had at least 1 child in elementary school (grades 1-6). Parents and children were included in a 1:1 ratio; a total of 113 450 parents and 113 450 children were included in the analysis. Statistical analysis was performed between March and April 2022.Main Outcomes and MeasuresThe main outcomes of interest were (1) parental acceptance of COVID-19 vaccination for their children and (2) its association with self-reported sufficiency and credibility of information about the vaccine. A multivariable logistic regression was used to evaluate factors associated with parental decision-making in favor of COVID-19 vaccination; path analysis was used to examine indirect effects of information sufficiency and credibility.ResultsOf the 113 450 children, 58 342 (51.4%) were boys, and the mean (SD) age was 10.1 (1.5) years. Of the 113 450 parents who responded, 7379 (6.5%) were accepting vaccination for their children; 15 731 (13.9%) reported the vaccine-related information they received was sufficient, and 23 021 (20.3%) reported the information was credible. Parents who reported that the information was sufficient were 3.08 times (95% CI, 2.85-3.33; P < .001) more likely to report being willing to vaccinate their children than those who believed the information was insufficient, and those who reported that the information was credible were 7.55 times (95% CI, 6.46-8.87; P < .001) more likely to report being willing to vaccinate their children than those who believed the information was not credible. Higher levels of information sufficiency and credibility were associated with perceptions of increased vaccine safety (sufficiency: β = 0.08; P < .001; credibility: β = 0.59; P < .001) and effectiveness (sufficiency: β = 0.05; P < .001; credibility: β = 0.60; P < .001).Conclusions and RelevanceIn this study, a significant association was found between self-reported sufficiency and credibility of vaccine-related information and parental decision-making regarding COVID-19 vaccination for their children, suggesting that communications and policies that provide sound information are essential to improve vaccination rates.