Achieving sustainable agricultural development is essential for ensuring stable global food supplies. Rural-urban migration, as a widespread socioeconomic phenomenon, introduces complexities and uncertainties to sustainable agricultural practices. This study constructs an analytical framework linking migration, large-scale farming, and sustainable agriculture, leveraging empirical evidence from 37,648 village-level samples in China. The findings demonstrate that rural-urban migration significantly enhances sustainable agriculture, as evidenced by increased mechanization and reduced fertilizer use, facilitated through large-scale farming. We further highlight the heterogeneity in large-scale farming decisions by agricultural entities under rural labor outmigration, shaped by economic rationality. Favorable production, distribution, and living conditions significantly amplify the positive impact of migration on large-scale farming, thereby contributing to enhanced sustainable agricultural outcomes. This study advances the understanding of the land-labor relationship under rural-urban migration and offers actionable insights for formulating policies to promote sustainable agricultural development.