Objectives <p>This study investigates the impact of adverse childhood experiences (ACEs) and depressive symptoms on incident arthritis in middle-aged and older Chinese adults, examining the mediating role of depressive symptoms in the ACEs–arthritis relationship to uncover psychological mechanisms underlying arthritis development.</p> Methods <p>We used 2011–2020 data from the China Health and Retirement Longitudinal Study (CHARLS) and included 4,184 participants aged ≥ 45&#xa0;years who were free of arthritis at baseline (2011). ACEs were evaluated with 11 types of childhood adversity, classified into quartiles, while depressive symptoms were measured using the CES-D scale. Multivariable logistic regression and stratified analyses assessed associations between ACEs, depressive symptoms, and incident arthritis. Restricted cubic splines and mediation analysis were applied to explore dose–response relationships and the mediating role of depression.</p> Results <p>Among 4184 participants, 969 developed incident arthritis. Individuals in the highest ACEs quartile (Q4) had a significantly higher arthritis risk (<i>OR </i>1.78, 95% CI 1.43–2.21, <i>P &lt; </i>0.001). This association was stronger in females and individuals aged 45–64. Depressive symptoms also increased arthritis risk, with a nonlinear dose–response relationship. Mediation analysis showed depressive symptoms partially mediated the ACEs–arthritis relationship, accounting for 12.4% of the effect.</p> Conclusions <p>In this national cohort, higher ACEs burden and greater depressive symptom severity were significantly associated with incident arthritis, and depressive symptoms partially mediated by the ACEs–arthritis association. Targeting childhood adversity and later-life mental health may help reduce arthritis risk in aging populations.</p>