Rapid conversion of agricultural land into housing challenges rural livelihoods and food security in many developing countries; however, its implications for agrarian injustice remain underexplored. This study investigates how unjust agricultural land conversion affects farmers’ welfare and household food insecurity in Kediri Subdistrict, West Lombok, Indonesia. Unjust agricultural land conversion relates to unequal land governance, weak spatial planning enforcement, and socioeconomic effects on smallholders. A convergent mixed-method approach is used to integrate multitemporal spatial analysis using Geographic Information Systems, household survey data from 100 farmers, qualitative interviews, and logistic regression modeling based on the Food Insecurity Experience Scale. The results reveal a substantial transformation of rural landscapes, with approximately 31% of productive agricultural land converted into housing between 2012 and 2024. This process undermines farmers’ livelihoods and intensifies food insecurity across availability, accessibility, and utilization dimensions. Logistic regression identified housing-driven land conversion as the strongest predictor of worsening food insecurity. Older and less-educated farmers exhibited significantly higher vulnerability. The findings demonstrate that farmland conversion is a physical land-use change and structural driver of food insecurity through land dispossession, livelihood erosion, and reduced household resilience. This study clarifies that unjust conversion reflects rapid land transformation driven by housing development, weak spatial planning control, and unequal effects on smallholders who experience livelihood loss without adequate protection or compensation. These findings highlight the need to strengthen spatial planning enforcement, protect sustainable agricultural land, and promote more inclusive land governance to safeguard rural livelihoods and food security.