Background: Parental involvement in mobile health (mHealth) to consult with medical professionals appears to be prevalent in China with the rapid development of the internet. More parents with busy jobs have chosen to use mHealth. During the ongoing COVID-19 outbreak, mHealth can assist with health promotion, directions for medication use, and disease diagnosis via online chat and video consultation without contacting others. To our knowledge, no studies have been performed to explore the role of mHealth in parents' attitudes toward child health care at home during the COVID-19 outbreak. Objective: This study aims to identify the associated factors of willingness to adopt mHealth among Chinese parents during the COVID-19 outbreak and to explore the correlation between the frequency of adopting mHealth and parents' attitudes toward child health care at home. Methods: Chinese parents were asked to complete an online survey from January 25 to February 15, 2020. The questionnaire comprised of two parts with a total of 16 items, including parents' demographic variables and attitudes toward child health care at home. By multivariate logistic regression, we explored factors associated with parents' willingness to adopt mHealth during the COVID-19 outbreak. Pearson chi-square tests were used to reveal the correlation between the frequency of adopting mHealth and parents' attitudes toward child health care at home. Results: A total of 254 parents enrolled, and 202 (79.5%) parents were willing to adopt mHealth during the COVID-19 outbreak. Parents' age (26-35 years: adjusted odds ratio [AOR] 8.114, 95% CI 1.471-44.764), parents' interest in the COVID-19 pandemic (moderate: AOR 8.753, 95% CI 2.009-38.127; high: AOR 22.194, 95% CI 5.509-89.411), the source that recommended mHealth (medical health providers: AOR 4.257, 95% CI 1.439-12.596), the presence of chronic disease in their children (yes: AOR 20.844, 95% CI 4.600-94.443), parents' duration of daily internet use (4-6 hours: AOR 6.487, 95% CI 1.870-22.495; >6 hours: AOR 8.766, 95% CI 1.883-40.804), and adoption of mHealth before the COVID-19 outbreak (yes: AOR 3.413, 95% CI 1.234-9.444) were significantly correlated with the parents' willingness to adopt mHealth during the COVID-19 outbreak. The frequency of mHealth use among parents was correlated with their behaviors in regard to handwashing (chi(2)(6) =18.967, P=.004), mask wearing (chi(2)(6) =45.364, P<.001), frequency of leaving the home (chi(2)(6) =16.767, P=.01), room disinfection and ventilation (chi(2)(6) =19.515, P=.003), temperature checking (chi(2)(6) =17.47, P=. 007), and mental health care of children (chi(2 )(6)=63.810, P<.001) during the COVID-19 pandemic. Conclusions: We found various objective factors that were associated with parents' willingness to adopt mHealth during the COVID-19 outbreak. Overall, parents' willingness to adopt mHealth was high. The frequency of mHealth use among parents was correlated with their attitudes toward child health care at home. The option of mHealth to patients at home during the COVID-19 outbreak would be beneficial for education and improvement in self-management of child health care at home.