Property rights systems serve as foundational institutional arrangements underpinning economic and social operations. Land tenure security exerts a profound influence on factor allocation efficiency and the behavioral decisions of economic agents. Nevertheless, few scholars have examined the quantitative relationship between land tenure insecurity and farmers’ cropland abandonment behavior—despite the fact that rural China is currently confronting both challenges concurrently. To address this research gap, this chapter adopts a panel random effects model to empirically investigate the impact of land tenure insecurity on cropland abandonment, utilizing three waves of panel data from the China Rural Household Panel Survey (2015–2019). Results show that land tenure insecurity significantly exacerbates cropland abandonment, increasing the proportion of abandoned cropland by an average of 0.70 percentage points. This effect is primarily driven by the fact that land tenure insecurity suppresses agricultural capital investment, reduces agricultural labor input, and impedes land transfer, thereby accelerating the spread of cropland abandonment. However, the impact of land tenure insecurity on cropland abandonment exhibits heterogeneity across horizontal income differentiation and vertical intergenerational disparities. Specifically, the adverse effects are more pronounced among higher-income farmers and the older generation, whereas lower-income farmers and the younger generation remain largely unaffected. Furthermore, formal institutions—exemplified by land certification—help mitigate the adverse effects of land tenure insecurity on cropland abandonment, while informal institutions, represented by village regulations, prove ineffective. Accordingly, future efforts should focus on strengthening the land tenure system, improving factor allocation efficiency, implementing tailored policies for different farm household groups, and advancing institutional coordination. This integrated approach will help alleviate the negative impacts of land tenure insecurity on land utilization and promote the sustainable development of agriculture.