Self-efficacy is an important factor associated with healthy lifestyle changes in heart failure treatment. Functional capacity testing of heart failure patients (HFPs) can stratify prognosis. Reduced functional capacities in HFPs are linked to a poor heart failure prognosis. Limited research has examined the potential relationship between self-efficacy and functional capacity. The aims of this study were to assess self-efficacy level and functional capacity among HFPs after hospitalization, and examine whether there is a relationship between them. A descriptive correlational design was used. A convenience sample of 220 HFPs was recruited from 2 hospitals in Jordan. The Arabic version of Cardiac Self-Efficacy Questionnaire was used to assess self-efficacy, the 6-Minute Walking Test (6-MWT) was used to assess functional capacity, and the Borg rating of perceived exertion scale (Borg Scale) was used to assess exertion during 6-MWT. The sample included 46.8% male (n = 103) and 53.2% female (n = 117). The mean age was 52.66 ± 8.91 years. Most of the HFPs were categorized based on New York Heart Association classification as class I, 35.9% (n = 79), and class II, 41.4% (n = 91). The mean ejection fraction was 41.46 ± 9.44. The global self-efficacy was moderate (32.98 ± 9.92), and the mean score for the 6-MWT was 494.35 ± 143.37. The Borg Scale mean was 10.94 ± 3.34. In addition, there was a positive relationship between self-efficacy and 6-MWT (r = 0.63, n = 220, P = .01). This study provides baseline data for further research on treatment of HFPs, and the development of evidence-based tailored health interventions to maintain and improve self-efficacy and functional capacity among these service users. Moreover, replicated researches can test the study results considering different methodologies, such as using objective functional capacity tool and longer follow-up periods.