Purpose: This study aimed to construct and test a hypothetical model of the quality of life of school-age children with asthma based on the health-related quality of life model by Wilson and Cleary. Methods: Data were collected from 205 pairs of pediatric outpatients diagnosed with asthma and their parents in Seoul and Gyeonggi-do from July 2016 to April 2017. The exogenous variables were asthma knowledge, number of accompanying allergic diseases, and social support. The endogenous variables were asthma self-efficacy, asthma symptom control, perceived health status, parental quality of life, and children’s quality of life. For data analysis, descriptive statistics, factor analysis, and structural equation modeling were performed. Results: Eighteen of the twenty-four hypotheses selected for the hypothetical model were attentive and supported statistically. Quality of life was explained by asthma self-efficacy, asthma symptom control, perceived health, parental quality of life, and asthma knowledge with 83.5%. Conclusion: Strategies for promoting self-efficacy and enforcing asthma knowledge will be helpful for the improvement of health-related quality of life with school-aged asthmatic children.