["Family Relations, EarlyView. ", "\nABSTRACT\n\nObjective\nThis study used longitudinal dyadic data to examine heterogeneous trajectories of marital satisfaction and their associations with depressive symptoms among Chinese couples coping with chronic illness.\n\n\nBackground\nChronic illness imposes substantial psychological and caregiving burdens on both patients and spouses. However, limited research has examined marital satisfaction trajectories, their heterogeneity, and their links with depressive symptoms in Chinese couples living with chronic illness.\n\n\nMethods\nDyadic latent growth curve modeling and Dyadic Latent Class Growth Analysis (DLCGA) were conducted among 3751 couples to examine average and heterogeneous developmental patterns of marital satisfaction. Parallel process latent growth modeling was used to investigate the co‐development of marital satisfaction and depressive symptoms. Distal depressive outcomes were compared across trajectory classes using the BCH approach, and covariates of class membership were examined using R3STEP.\n\n\nResults\nMarital satisfaction remained relatively stable on average for both patients and spouses, but three distinct trajectory classes emerged: Patient‐Moderate Increasing/Spouse‐Low Increasing (11.01%), Patient‐High Stable/Spouse‐High Declining (79.37%), and Patient‐Low Declining/Spouse‐High Declining (9.62%). Depressive symptoms declined over time in both partners. Higher initial marital satisfaction was associated with lower initial depressive symptoms, and depressive changes were synchronized within couples. Distal depressive outcomes and trajectory membership differed by demographic, illness‐related, and psychological factors.\n\n\nConclusions\nMarital satisfaction may function as a protective relational resource in couples coping with chronic illness.\n\n\nImplications\nGreater attention to dyadic marital patterns may inform family‐based interventions and help identify vulnerable couples.\n\n"]