There is a lack of comprehensive research on the topic of knowledge, attitude, and practice (KAP) among heart failure patients. This study aimed to investigate the patients’ KAP toward heart failure (HF). This web-based cross-sectional study was conducted among HF patients, using a self-administered questionnaire. A total of 483 valid questionnaires were enrolled, including 254 (52.59%) males. The mean KAP scores were 10.75 ± 3.44 (possible range: 0–20), 22.93 ± 2.43 (possible range: 8–40), 32.21 ± 4.34 (possible range: 8–40), respectively. Multivariate logistic regression showed that knowledge and heart failure mid-range ejection fraction were independently associated with proactive practice. The SEM analysis showed that education exhibited a positive effect on knowledge, while medical insurance showed a notable negative effect on knowledge. Furthermore, left ventricular ejection fraction #10 score demonstrated a positive effect on knowledge, and marital status had a significant positive effect on knowledge. Additionally, kidney disease emerged as a positive effect on practice, while attitude was found to have a negative effect on practice. HF patients had inadequate knowledge, negative attitude and proactive practice towards HF. Targeted educational initiatives, mental health support, and interventions addressing comorbidities and lifestyle changes are recommended to be integrated into HF management protocols.