Background <p>Effective diabetes management in later life requires active patient engagement. Self-advocacy has been proposed as a psychological resource that supports active disease management, while eHealth literacy may represent a key pathway linking self-advocacy to self-management. However, the mechanisms underlying these associations remain insufficiently examined in older adults with diabetes. This study aimed to investigate the mediating role of eHealth literacy in the relationship between self-advocacy and self-management among older adults with diabetes.</p> Methods <p>A total of 349 older adults with diabetes (mean age of 69.37 ± 7.73 years) were recruited from a tertiary hospital in southern China through convenience sampling. Participants completed validated instruments, including the Seniors Empowerment and Advocacy in Patient Safety scale, the eHealth Literacy Scale, and the Summary of Diabetes Self-Care Activities scale. Pearson correlation analysis was used to explore associations, and the PROCESS macro in SPSS was employed to test the mediating role of eHealth literacy.</p> Results <p>Self-advocacy, eHealth literacy, and self-management were all at suboptimal levels among older adults with diabetes. Mediation analysis showed that eHealth literacy partially mediated the relationship between self-advocacy and self-management, with the indirect effect accounting for 31.11% of the total effect.</p> Conclusions <p>eHealth literacy is an important mechanism through which self-advocacy enhances diabetes self-management in later life. Interventions that incorporate eHealth literacy training may strengthen the benefits of self-advocacy and improve health outcomes in older adults with diabetes.</p>