Riparian zones, as critical ecotones in riverscape, serve as key transitional interfaces between aquatic and terrestrial ecosystems, and have increasingly been identified as focal points for biological invasions. The morphology of the riparian zones, particularly variations in shape and curvature of riparian habitats, strongly governs how alien plant species establish, spread, and persist. Yet, it is evident that the earlier studies have been deficient in addressing how invasiveness of alien plants are influenced by riparian morphology, leaving a conspicuous gap in our understanding and hampering the design of effective control measures. To address this shortfall, this study combined high-resolution remote sensing imagery with intensive ground field surveys carried out from 2021 to 2022 across about 660 km of the riparian zones in China’s Three Gorges Reservoir. Within the riparian zones, 260 sampling plots were established and classified each riparian segment by both its overall morphology, including concave, convex, wavy, or straight, and its quantitative curvature. Then we tallied the presence and abundance of alien plants, assigning each taxon to one of four invasion grades (I–IV) based on a national guideline. The effects of riparian morphology and curvature on the distribution patterns of invasive plants across the four invasion grades were systematically tested. In general, Chi-square tests (P < 0.001) and Kruskal-Wallis tests (P < 0.05) revealed significant differences in the distribution patterns of alien plants across different invasion grades, depending on the morphology and curvature of riparian zones. Especially, the results indicated that: 1) wavy riparian shape, characterized by frequent hydrodynamic disturbance and unstable soil structure, promoted the dominance of Grade I invasive species which possess broad ecological niches, high dispersal ability, and strong competitive advantages. In contrast, concave shapes favored Grade II-III invaders with moderate invasiveness through sediment enrichment and hydrological stability; 2) high-curvature shapes selected for the colonization of plants with medium invasiveness through sediment deposition and resource heterogeneity, whereas low-curvature shapes were colonized primarily by highly competitive Grade I invaders under intense hydrological disturbance and limited resource availability; 3) straightened shapes (e.g., chan-nelized riverbanks) became the primary distribution areas for invasive plants across all grades in 2022 due to niche vacancies caused by anthropogenic disturbances. From these results, we advance the notion of “orderly invasion” wherein riparian morphology acts as a sequen-tial environmental filter that sorts alien plants along gradients of disturbance, substrate stability, and resource distribu-tion. Species with differing niche demands and invasiveness thus occupy predictable positions within the riparian mosaic. Recognizing this orderly structure has practical value, it supplies a mechanistic framework for risk-based, tiered management. Managers can prioritize monitoring of wavy or straightened riparian zones for early detection of high-risk invaders while tailoring restoration efforts in concave riparian zones to intercept mid-grade invasive species before they ascend to dominance. Ultimately, integrating morphological metrics into invasive-species risk assess-ments will sharpen our capacity to safeguard riparian ecosystems amid continued hydrological alteration and escalat-ing human pressure.