Struggling with heart failure (HF) may be a distressful experience for the entire family. As a key variable contributing to positive family functioning, family hardiness can protect against HF-related harm. Thus, recognizing factors associated with family hardiness could promote strategies that enable successful adaptation to HF. This study aimed to explore protective factors linked to family hardiness among HF patients.A cross-sectional study was undertaken in 2020 among 167 HF patients in Nanjing, China. The study measures comprised a self-designed general information questionnaire, the Family Hardiness Index, the Mutuality Scale, the Positive and Negative Affect Scale, and the Simplified Coping Style Questionnaire. The data analysis was performed using IBM SPSS, version 25 and comprised Pearson's correlation analysis, a multiple linear regression model, and an analysis of mediating effects.The average Family Hardiness Index score for the 167 HF patients was 57.95 ± 11.41. The multiple linear regression analysis revealed that mutuality, active coping style, and positive emotions of HF patients positively predicted family hardiness (β = 0.359, 0.308, and 0.215, respectively; all P ˂ 0.05). Mutuality between patients and family members had partial mediating effects between active coping style, positive emotions, and family hardiness.Our results revealed that patients' active coping styles, positive emotions, and mutuality were protective factors associated with family hardiness. In light of our findings, we suggest that active coping strategies, positive emotions, and, especially, closer relationships within families should be encouraged during the rehabilitation and follow-up care of HF patients.