Wetland restoration represents a key technical strategy for reversing lake ecosystem degradation and restoring ecological functions. By enhancing hydrological connectivity and optimizing landscape patterns, it can substantially improve habitat quality for waterbirds. Huangpi Lake is a small shallow lake in the middle and lower Yangtze River floodplain that has experienced severe landscape fragmentation and ecological degradation due to long-term anthropogenic disturbances such as aquaculture reclamation. The wetland restoration project was carried out in the study area between June 2023 and June 2024. However, a systematic assessment of its ecological impacts is still lacking. From the perspective of waterbird functional groups, this study systematically examined the dynamics of wintering waterbird communities before and after restoration, and evaluated the effects of landscape pattern changes on waterbird assemblages by integrating landscape configuration and composition. The results demonstrated that the landscape pattern of the lake wetland was substantially optimized following restoration. During the early wintering period, overall patch density decreased by 48.93%, water area expanded by 53.49%, and the number of mudflat patches declined by 53.89%; in the mid-wintering period, the number of water patches decreased by 71.31%; and in the late wintering period, the vegetation aggregation index increased by 12.45%. Waterbird functional groups showed differential responses to variations in landscape patterns. Increases in the water area aggregation index promoted population growth in predatory diving waterbirds (G1); higher mudflat aggregation index effectively increased colony size in herbivorous waterbirds (G5); whereas an elevated shallow-water aggregation index caused habitat homogenization, leading to population declines in small benthivorous waders (G3), which depend on such heterogeneous patches. Generalized Additive Model (GAM) analysis indicated that patch density represented the key landscape configuration factor governing the population dynamics of G5, whereas water area and aggregation index served as the dominant drivers shaping the distribution of diving waterbirds and large waders. To restore small shallow lake wetlands, landscape patterns should be optimized by enhancing hydrological connectivity and staged water level regulation to meet the wintering needs of different waterbird functional groups. This study highlights the importance of constructing heterogeneous habitat mosaics during wetland restoration for the effective conservation of wintering waterbirds, and provides theoretical support and practical implications for the scientific restoration of heavily human-disturbed wetlands and the protection of waterbird habitats in the middle and lower Yangtze River floodplain.