Enhancing farmers' collective action amid ongoing transformations in land management practices is crucial for achieving rural revitalization. In this study, a social–ecological system analytical framework is constructed to examine the mechanisms through which land trusteeship influences the collective action of farmers in the Chinese context. Land trusteeship was found to encompass three processes of socialization of farmland use, management process, and output, reflecting a broader concept of socialized farmland operation. By using survey data collected in 2023, from 1809 households across 122 villages in 19 Chinese provinces, ordered probit regression, instrumental variable methods, restricted cubic spline regression, and mediation effect models were employed. The findings indicate that: (1) Land trusteeship significantly and positively impacts farmers' collective action. (2) Increasing the scale of land trusteeship does not constrain farmers’ collective action, and results are consistent across various models, samples, and dependent variables. (3) Land trusteeship promotes collective action by enhancing village leadership and fostering the development of cooperative organizations. These findings provide a new perspective on collective action related to land management practices and offer theoretical insights for agricultural transition economies seeking to advance agricultural modernization. Future innovations in land trusteeship should focus on accelerating technological upgrades, optimizing agricultural production conditions, and implementing policy measures to guide diverse stakeholders, including farmers, village leaders, and market entities, to collaborate in rural governance and development.