This study investigates the association between activities of daily living (ADL) limitation and cognitive impairment with depression among Chinese older adults aged 65 and above, and tests their interaction on both additive and multiplicative scales. Data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) were used, including 11,025 eligible participants. Logistic regression models were fitted, and both multiplicative and additive interactions for ADL limitation and cognitive impairment were tested. Results showed that 27.4% of participants reported depressive symptoms. After controlling for potential confounding factors, ADL limitation and cognitive impairment were both positively associated with depression. The adjusted additive interaction of basic and instrumental activities of daily living limitation were 2.47 (95%CI:1.92–3.19) and 3.67 (95%CI:2.88–4.66), respectively, but the multiplicative interaction items were both insignificant. The study concludes that ADL limitation and cognitive impairment are both risk factors for depression among Chinese older adults. Moreover, the significant interaction of ADL limitation and cognitive impairment was found in the additive model, suggesting that improving ADL may be helpful in reducing the risk of depression among older people with cognitive impairment. The study also found that the combined effect of ADL limitation and cognitive impairment was greater than their individual effect. The study highlights the importance of addressing ADL and cognitive impairment to reduce the risk of depression in older adults. The findings suggest that interventions aimed at improving ADL and cognitive function may be beneficial in reducing the risk of depression in older adults. The study also notes that the results may be influenced by self-reported data and the cross-sectional design, which limits the ability to establish causality. The study recommends further research to develop advanced smart devices to improve ADL and to promote family support for older adults to alleviate depressive symptoms. The study also suggests that physical rehabilitation and psychological interventions should be added to basic public health services. The study concludes that the interaction between ADL limitation and cognitive impairment on depression was statistically significant in the additive model, indicating that improving ADL among older people with cognitive impairment may help reduce the risk of depression.This study investigates the association between activities of daily living (ADL) limitation and cognitive impairment with depression among Chinese older adults aged 65 and above, and tests their interaction on both additive and multiplicative scales. Data from the Chinese Longitudinal Healthy Longevity Survey (CLHLS) were used, including 11,025 eligible participants. Logistic regression models were fitted, and both multiplicative and additive interactions for ADL limitation and cognitive impairment were tested. Results showed that 27.4% of participants reported depressive symptoms. After controlling for potential confounding factors, ADL limitation and cognitive impairment were both positively associated with depression. The adjusted additive interaction of basic and instrumental activities of daily living limitation were 2.47 (95%CI:1.92–3.19) and 3.67 (95%CI:2.88–4.66), respectively, but the multiplicative interaction items were both insignificant. The study concludes that ADL limitation and cognitive impairment are both risk factors for depression among Chinese older adults. Moreover, the significant interaction of ADL limitation and cognitive impairment was found in the additive model, suggesting that improving ADL may be helpful in reducing the risk of depression among older people with cognitive impairment. The study also found that the combined effect of ADL limitation and cognitive impairment was greater than their individual effect. The study highlights the importance of addressing ADL and cognitive impairment to reduce the risk of depression in older adults. The findings suggest that interventions aimed at improving ADL and cognitive function may be beneficial in reducing the risk of depression in older adults. The study also notes that the results may be influenced by self-reported data and the cross-sectional design, which limits the ability to establish causality. The study recommends further research to develop advanced smart devices to improve ADL and to promote family support for older adults to alleviate depressive symptoms. The study also suggests that physical rehabilitation and psychological interventions should be added to basic public health services. The study concludes that the interaction between ADL limitation and cognitive impairment on depression was statistically significant in the additive model, indicating that improving ADL among older people with cognitive impairment may help reduce the risk of depression.