To address ecological degradation in estuarine coastal wetlands caused by the combined pressures of land–sea interactions and anthropogenic activities, we developed an improved Coastal Wetland Ecological Status Index (CWESI). Using Landsat time-series observations from 1994 to 2024, together with the coefficient of variation (CV), Theil–Sen slope estimator, Mann–Kendall significance test, and Hurst exponent, we quantified the spatiotemporal dynamics and persistence characteristics of ecological quality in the Liaohe Estuary coastal wetland. Furthermore, an optimal parameter-based geographical detector (OPGD) model was employed to investigate the relative contributions and interactive effects of natural and anthropogenic factors on ecological quality heterogeneity. The results revealed the following: (1) Ecological quality exhibited an overall fluctuating improvement trend during 1994–2024, with the mean CWESI value increasing from 0.45 to 0.52. Spatially, ecological quality displayed a decreasing gradient from inland areas towards coastal zones, with high-quality ecological patches primarily concentrated in reed wetlands and core conservation areas. (2) During the study period, the area of low-quality ecological spaces decreased by 75.23 km², whereas areas classified as Moderate or higher expanded by 74.96 km². Approximately 78.66% of the study area exhibited stable or improving ecological conditions, while only 5.23% experienced ecological degradation. (3) Driver analysis indicated that fractional vegetation cover and net primary productivity were the dominant natural factors influencing ecological quality. Their interactions with soil moisture and climatic variables exhibited significant bivariate enhancement effects. These results show that wetland ecological quality is regulated by the synergistic interactions among multiple environmental factors. Long-term ecological restoration measures, including aquaculture withdrawal and wetland rehabilitation as well as ecological water replenishment projects, acted as critical anthropogenic drivers promoting sustained ecological improvement. The proposed CWESI framework provides a robust methodological basis for dynamic monitoring, conservation planning, and adaptive ecological management of coastal wetlands facing similar environmental pressures.