Self-efficacy plays an essential role in increasing health-promoting behaviour among older adults with chronic illness. Chronic illness requires high self-efficacy to manage the disease appropriately. Hence, the purpose of this study is to identify the relationship between self-efficacy and health-promoting behaviour among older adults with chronic illness. A cross-sectional study was conducted using a self-administered questionnaire to 218 older adults. The results from this study found a relationship between self-efficacy and health-promoting behaviour exists at rho 0.28 and p-value 0.001. This study revealed that self-efficacy strongly relates to health-promoting behaviour among older adults.