Background <p>Chronic heart failure (CHF) can lead to significant psychological changes, including a decrease in the sense of well-being in patients. This study aimed to determine the effect of a positive psychology skill enhancement program on the sense of well-being in patients with CHF.</p> Methods <p>In this randomized controlled trial, 78 hospitalized patients with CHF at Chamran Medical Center in Isfahan were randomly assigned to an intervention group (<i>n</i> = 39) and a control group (<i>n</i> = 39). The positive psychology skill enhancement program was implemented over six sessions. Both groups completed the Oxford Happiness Inventory before the intervention, immediately after, and one month later. Data were analyzed using repeated measures ANOVA to assess within-group and between-group changes over time.</p> Results <p>The repeated measures ANOVA revealed a statistically significant interaction between time and group membership (F = 616.57, <i>p</i> &lt; 0.001, η² = 0.827), indicating that changes in well-being scores differed between the intervention and control groups. In the intervention group, mean well-being scores increased significantly from baseline (M = 30.68, SD = 8.51) to immediately after the intervention (M = 53.06, SD = 5.31) and were sustained one month later (M = 44.35, SD = 6.80). In contrast, the control group showed no significant changes over time (<i>p</i> &gt; 0.05).</p> Conclusions <p>The positive psychology skill enhancement program significantly improved well-being in patients with CHF, with effects persisting one month post-intervention. However, given the study’s limitations, including its short follow-up period and single-center design, further research is recommended to confirm these findings in broader settings.</p> Trial registration <p>Clinical trial registration code was IRCT20180601039934N2 on April 8, 2023.</p>