BACKGROUND: Chronic heart failure (CHF) is a progressive and recurrent condition associated with high hospitalization rates, substantial healthcare burden, and impaired quality of life. Health-promoting behaviors are essential for long-term disease management in patients with CHF, yet their formation and maintenance are often constrained by individual capability, external support, and motivational factors. OBJECTIVE: This study aimed to examine the current status and associated factors of health-promoting behaviors among patients with chronic heart failure and to clarify the pathways among related factors. METHODS: A cross-sectional design was used to investigate health-promoting behaviors and their associated factors among patients with CHF. The study was conducted from December 2024 to November 2025 in two tertiary Grade A hospitals in Shanghai. Convenience sampling was used, and 320 questionnaires were distributed; 302 valid questionnaires were included, yielding a valid response rate of 94.38%. The instruments included a general information questionnaire, the Health-Promoting Lifestyle Profile, the Perceived Social Support Scale, the Heart Failure-Specific Health Literacy Scale, and the Health Activation Scale. SPSS version 26.0 was used for descriptive statistics, univariate analysis, and multiple linear regression. AMOS version 23.0 was used for path analysis, and Python version 3.9 was used for random forest-based feature importance ranking. RESULTS: The total health-promoting behavior score was 126.00 (116.00, 137.00), and the mean item score was 2.42 (2.23, 2.63), indicating an overall moderate level; the largest proportion of patients was classified as moderate (52.32%). Among the dimensions, self-actualization had the highest score, whereas physical activity had the lowest score. Health literacy was at a moderate level, perceived social support was at a high level, and health activation was at a low level. Univariate analysis showed significant differences in health-promoting behavior scores by age, educational level, employment status, marital status, living arrangement, monthly per capita household income, type of medical insurance, disease duration, number of comorbidities, and number of hospitalizations in the past year (p < 0.05). Health-promoting behaviors were positively correlated with health literacy, perceived social support, and health activation (p < 0.01). Multiple linear regression analysis showed that monthly per capita household income, type of medical insurance, number of comorbidities, number of hospitalizations in the past year, employment status, health activation, perceived social support, and health literacy were independently associated with health-promoting behaviors, jointly explaining 68.7% of the variance. Mediation analysis showed that health activation partially mediated the associations of health literacy and perceived social support with health-promoting behaviors. Nonlinear analysis further suggested that number of hospitalizations in the past year, health activation, perceived social support, and health literacy were key features associated with health-promoting behaviors. CONCLUSION: Health literacy, perceived social support, and health activation were key factors associated with health-promoting behaviors among patients with CHF. Health activation served as a significant mediator linking health literacy and perceived social support with health-promoting behaviors. Future interventions should focus on improving health literacy, strengthening social support systems, and enhancing health activation to promote the development and maintenance of health-promoting behaviors among patients with CHF.