Background <p>The significance of spiritual well-being and happiness in promoting overall health among older adults with chronic illnesses cannot be ignored. This research aimed to explore the correlation between spiritual health and happiness in elderly patients suffering from chronic disease who were admitted to the Comprehensive Health Center in Babol City in 2023.</p> Methods <p>This study employed a descriptive and cross-sectional research design. A sample of 225 elderly individuals with chronic diseases was selected through convenience sampling from four comprehensive health centers in both urban and rural areas. Data were collected using the Spiritual Well-Being Questionnaire (SWB) and the Oxford Happiness Questionnaire. Statistical analyses were performed using descriptive and inferential statistics, including the Pearson correlation coefficient, independent t-test, analysis of variance, and regression analysis, utilizing SPSS version 20.</p> Results <p>The results indicated that the average scores for spiritual health (109.98 ± 12.58) and happiness (79.89 ± 11.82) were significantly high. A strong and statistically significant correlation was found between spiritual health and happiness (<i>P</i> &lt; 0.001, <i>r</i> = 0.967). Regression analysis revealed that spiritual health accounts for 93.5% of the variance in happiness among the elderly.</p> Conclusion <p>Enhancing spiritual health in older adults is linked to higher levels of happiness. It is essential to incorporate spiritual health considerations into health interventions designed for the elderly population.</p>