Objective: To explore the application effect of smart wearable devices in the management of elderly chronic diseases and their user acceptance, with a view to providing new technical support for the health management of elderly patients with chronic diseases. Methods: In this study, a randomized crossover controlled trial design was adopted, and 500 elderly chronic disease patients in Xi’an City were selected as the study subjects during the period from January 2023 to January 2024, and the study subjects were randomly divided into 250 each in the control group and the observation group. The study was divided into two phases of 8 weeks each, with a 4-week washout period in the middle. In the first phase, the control group used traditional health monitoring methods and the observation group used smartwatches with physiological monitoring functions for daily health data monitoring; in the second phase, the two groups switched roles, i.e., the control group used smart wearable devices and the observation group returned to traditional monitoring methods. Through questionnaires, interviews, and physiological data collection, the application effect and user acceptance of smart wearable devices were evaluated. The study data included patients’ physiological indicators such as heart rate, blood pressure, and sleep quality, as well as patients’ satisfaction, frequency of use, and adherence to smart wearable devices. Results: In the first stage, patients in the observation group who used smartwatches had significantly higher accuracy in heart rate, blood pressure, blood glucose, and sleep quality monitoring than those in the control group (P < 0.05). The observation group’s satisfaction score (out of 5) with the smartwatch was significantly higher than the control group’s (P < 0.05). The frequency of smart wearable device use and adherence were also significantly higher in the observation group than in the control group (P < 0.05). After the second phase of role-swapping, the original control group showed improved monitoring accuracy and adherence during the smart device use phase, whereas the original observation group showed a decrease in these indicators after returning to traditional monitoring methods, but user satisfaction and adherence remained higher than they had been in the first phase. Conclusion: Smart wearable devices have significant application effects in the management of chronic diseases in the elderly, can effectively improve patients’ health management compliance and satisfaction, and have a high degree of user acceptance. Therefore, smart wearable devices are expected to become an important tool for the health management of elderly chronic disease patients.