Objective: To assess the self-care of patients with heart failure (HF), reliable and validated instruments are needed. The aim of this study was to test the validity and reliability of the Danish version of the European Heart Failure Self-care Behavior Scale (EHFScBS-9) based on previous studies reporting 1, 2 and 3 factors, respectively. Methods: A convenience sample of 147 patients with HF completed the EHFScBS-9. Psychometric properties of the Danish version of the EHFScBS-9 were tested with factor loadings, factor correlations and goodness-of-fit indices for four different measurement models based on confirmatory factor analysis. Results: All of the items, except item 9 about regular exercise, demonstrated satisfactory item-total correlation ≥0.30. Regarding the fit of the models on the sample data, the most superior fit was observed for the two-factor solution in terms of root-mean-square error of approximation (RMSEA), goodness-of-fit index (GFI), adjusted GFI (AGFI) and comparative fit index (CFI), which all reached the predefined threshold value, except for the normed fit index (NFI) at 0.90. Factor score determinacy (FSD) for the four models tested was 0.88 for the one-factor solution, 0.54 and 0.87 for the two-factor model, 0.83–0.55 for the first three-factor model and 0.87–0.38 for the second three-factor model. Conclusions: The EHFScBS-9 questionnaire is a valid and reliable instrument to assess heart failure-specific self-care behaviours in a Danish population.