This study aimed to examine the effect of Health app literacy on app usage satisfaction among adults aged 20–59 who use health management applications. Data were collected via an online survey from September 3 to September 19, 2025, yielding 240 responses. The collected data were analyzed using SPSS 21.0, including frequency analysis, factor analysis, reliability analysis, correlation analysis, and multiple regression analysis. Descriptive results showed that gender and age were evenly distributed, with a higher proportion of metropolitan residents and four-year college graduates. Participants generally reported good health status and weight management practices. Reliability analysis indicated high internal consistency for Health app literacy (Cronbach’s α = .907) and app usage satisfaction (Cronbach’s α = .933). The mean score for literacy was 3.70, with the highest satisfaction for personalized information and the lowest for reliability. The mean usage satisfaction was 3.42, with app experience rated highest and nutrition management lowest. Correlation and regression analyses revealed significant positive associations between Health app literacy and usage satisfaction, with expertiseand reliabilitybeing the most influential factors, whereas personalized information provisionwas not statistically significant. These findings suggest that users’ perception of the scientific basis and reliability of app-provided information is critical for satisfaction, highlighting the importance of professional, reliable content and functional design in the development of Health apps.