Objective: The aim of this study was to determine the effect of psychosocial adjustment of heart failure patients on their self-care behaviors. Methods: The sample of the study consisted of 130 patients who applied for heart failure diagnosis at a state hospital’s cardiology outpatient clinic, cardiology clinic, and coronary intensive care unit between March and August 2017 and met the research criteria. Data about the patients were collected through a descriptive form, the Psychosocial Adjustment to Illness Scale—Self-Report, and the European Heart Failure Self-Care Behavior Scale -12. The analysis of the data was carried out using frequency, mean, standard deviation, the Mann–Whitney U test (U), Kruskal–Wallis test (X2 ), independent samples t-test, and one-way analysis of variance. Results: The mean Psychosocial Adjustment to Illness Scale—Self-Report total score of the patients was 51.1 ± 17.3. Among the Psychosocial Adjustment to Illness Scale—Self-Report sub-domains, the vocational environment received the highest mean score with 10.4 ± 3.9, while the extended family relationships received the lowest. The mean European Heart Failure Self-Care Behavior Scale total score was 31.2 ± 5.6. While there was no statistically significant relationship between Psychosocial Adjustment to Illness Scale—Self-Report and European Heart Failure Self-Care Behavior Scale, a weak positive correlation was found between the healthcare orientation sub-domain and European Heart Failure Self-Care Behavior (P > .05). Conclusion: While the self-care behaviors of the patients were at a sufficient level, their psychosocial adjustment was at a bad level. A positive significant relationship was found between self-care behaviors and healthcare orientation