<p>Under the impacts of global warming and the frequent occurrence of extreme climate events, the adaptability issue between water resources and land resources has become increasingly severe, which has affected the sustainable development of regional territorial space. Particularly in ecologically fragile areas, this mismatch problem is further amplified, leading to reduce cropland productivity, decrease efficiency of water and land resource utilization, and weaken ecological environment carrying capacity. Consequently, this has hindered regional sustainable development and food security. Therefore, based on the objective of maximizing ecological-economic-social (EES) benefits, this study constructed a multi-objective optimal allocation model of water and land resources for the Western Jilin Province (WJP). The third-generation Non-dominated sorting genetic algorithm (NSGA-III) was adopted to solve the model, thereby obtaining optimal allocation schemes of water and land resources under different objectives conditions. The results indicated that: (1) Multi-objective collaborative optimization was an effective approach to achieve regional sustainable development. The scenario of synergistic optimization of EES objectives can realize the improvement of economic benefits and social benefits while minimizing the reduction of ecological benefits (0.10%), reflecting the advantage of “synergistic enhancement” among the objectives. (2) Under the scenario of collaborative optimization of EES objectives, the optimal results of water and land resources demonstrated the potential for coordinated development of ecological restoration and agricultural production in the WJP. (3) A comparison of the data from various districts and counties of WJP before and after optimization highlights the necessity of differentiated resource allocation schemes, and the final optimization results also showed significant ecological restoration potential.</p>