Against the backdrop of accelerating urbanization and increasing population mobility in China, resettled migrants serve as a critical lens for understanding the ongoing restructuring of urban–rural relations. These migrants commonly face spatial, institutional, and social "triple disembedment", their livelihood adaptation critically determines the success of new-type urbanization and rural revitalization. Livelihood adaptability, as a core perspective for understanding and enhancing the sustainable development capacity of migrants, has become an important topic within research on global change and migration studies. However, existing studies remain limited to static analyses under the sustainable livelihood framework, lacking systematic investigation into the dynamic process of “risk exposure–adaptive response–strategy feedback”. This gap calls for a systematic, dynamic, and spatially-sensitive re-examination of migrants' behavioral logic and adaptation mechanisms. To address this gap, this study focuses on Wuwei City, a typical ecologically fragile and migrant-host area on the northern foothills of the Qilian Mountains. It develops a "risk–process–outcome" analytical framework to systematically examine migrants' livelihood adaptation through five core elements: livelihood risks, adaptive capacity, adaptation strategies, adaptation outcomes, and return intention. Focusing on three major resettlement sites in Wuwei City, this research integrates questionnaires, in-depth interviews, and logistic regression modeling to analyze migrant adaptation strategies and return decisions under compounded ecological, economic, and policy risks. The study aims to address gaps in existing research regarding temporal linkages, actor interactions, and spatial embeddedness, thereby providing an evidence-based for stable migrant resettlement in ecologically fragile zones. The findings indicate: ① Migrants in Wuwei City faced a convergent structure of livelihood risks, centered on high living costs, poor-quality redistributed farmland, and the risk of returning to poverty, all rooted in the “hidden deprivation” of land resources. ② Migrants in Wuwei demonstrate relatively high adaptive capacity and external support. They predominantly adopted aid-based and autonomous strategies to cope with economic risks, while their long-term livelihood planning primarily consists of expansion and transfer strategies. These strategic preferences are significantly shaped by government attention and support. ③ Return intention is more pronounced among migrants in Tianzhu Tibetan Autonomous County and pure agricultural households. Migrants who chose the “aid + transfer” strategy for economic risk adaptation were more inclined to "move back". ④ Return decisions reflect a “subsistence rationality” trade-off: while the superposition of economic risks and the interaction between health and welfare risks significantly strengthen the desire to return, the involvement of policy risks may trigger an "entitlement locking" effect that discourages return. This study proposes a classification system of livelihood risks and adaptation strategies specifically for migrants, revealing the underlying decision-making logic that "subsistence security outweighs income growth" for migrants. By expanding the dynamic explanatory dimension of the sustainable livelihood theory, our findings provide scientific basis and case support for optimizing resettlement policies, reducing the risk of returning to poverty, and promoting settlement stability. Accordingly, we recommend a shift from singular interventions to an integrated policy approach built on three pillars: land security, capacity building, and risk buffering. Such a systemic empowerment strategy is essential for rebuilding migrants' livelihood resilience and facilitating a fundamental transition from passive relocation to active rootedness.