This study delves into the intricate dynamics of South Korea’s grain production and trade, specifically scrutinizing water resource management and sustainability trends from 1991 to 2022. The primary objective was to assess the temporal evolution of South Korea’s agricultural virtual water trade in maize, soybeans and wheat. Employing the virtual water flows assessment method, water stress index, and an unsustainable import fraction (UIF) analysis, this research aimed to uncover key patterns and dynamics within the agricultural grain trade landscape. Utilizing comprehensive datasets encompassing grain trade, as well as water and land footprint data, this study assessed the intricate interplay between agricultural production, trade, and resource utilization. Results showed a reduction in local production for soybeans and a slight increase in domestic wheat production over the study period. In addition, the study revealed an overall increase in the virtual water imports associated with grain crops, with maize exhibiting the steepest upward trend in comparison with the other grains (wheat and soybeans). Furthermore, the study demonstrated that the import of maize contributed the highest amount of water and land savings, implying that this grain crop had the most significant impact on conserving local water and land resources. Environmental impact assessments, including water stress indices and the unsustainable import fractions, contributed to a comprehensive understanding of grain trade sustainability with concrete result values and insights, highlighting the intricate interplay of international grain trade and local water resource conservation in South Korea. By scrutinizing the virtual land and water dimensions of grain trade, this research offers valuable insights for policymakers and researchers striving to navigate the nexus of agriculture, trade, and resource management. The findings hold significance in the context of ensuring food security, optimizing resource allocation, and fostering sustainable agricultural practices in a dynamically evolving global landscape.