Background Relaxation techniques can reduce sympathetic nervous system activation and stress, potentially improving heart failure patients’ physical and psychological outcomes. Purpose To examine the effects of biofeedback-assisted relaxation (BFAR) therapy in patients with heart failure. Methods A prospective randomized control study was conducted. Participants in the treatment group received BFAR therapy, while participants in the control group received standard of care. Short-term outcomes were physical symptoms and psychosocial variables measured at baseline and 3 months; long-term outcomes were cardiac events and mortality assessed at 12 months. Results Fifty-two heart failure patients participated in the study: 23 (mean age 60.0 ± 13.7 years; 60.9% male; 39.1% New York Heart Association III/IV) in the treatment group and 29 (mean age 59.2 ± 12.2 years; 72.4% male; 48.3% New York Heart Association III/IV) in the control group. Short-term effects of BFAR on outcome variables were not significantly different between treatment and control groups. However, longer event-free survival was found in the treatment group compared with the control group ( p = .019). Conclusions/Implications for Practices BFAR therapy is effective to improve cardiac event-free survival of heart failure patients and can be applied to clinical setting.