Abstract: Cultivated land abandonment has become a major land use problem affecting China’s food security. Under the current production structure where large-scale farmers and smallholder farms coexist, the external economies of scale generated by the development of large-scale farmers can influence other agricultural producers within the region, thereby presenting new opportunities to mitigate cultivated land abandonment. Using data from the China Rural Revitalization Survey, this study adopted an exogenous perspective and employed methods such as 2SLS and IV-Probit to empirically examine the effects of the development of large-scale farmers on the cultivated land abandonment behavior of smallholder farmers and decipher the underlying mechanisms. It further analyzed heterogeneous effects across different characteristics. The findings revealed that: 1) In the sample, 4.21% of cultivated land was abandoned, with 9.25% of households engaging in the abandonment behavior, averaging 0.42 mu (1 mu ≈ 666.7 m2) of abandoned cultivated land per household. Large-scale farmers accounted for an average of 2.71% of all farmers. 2) An increase in the proportion of large-scale farmers within a region significantly suppressed both the proportion of abandoned cultivated land among smallholder farmers and their decision to abandon cultivated land. This effect was achieved through two paths: land transfer and the purchase of agricultural socialized services. 3) Topographical differences, differentiation differences, and generational factors partially influenced the role of large-scale farmer development in shaping the cultivated land abandonment behavior of smallholder farmers within a region. Compared with that of farmers in plains areas, non-agricultural farmers, middle-generation farmers, and older-generation farmers, the increase in the proportion of large-scale farmers within a region exerted pronounced inhibitory effects on the proportion of abandoned cultivated land and the decision to abandon cultivated land among farmers in hilly and mountainous areas, part-time farmers, full-time farmers, and younger-generation farmers. Therefore, to effectively curb the trend of cultivated land abandonment and safeguard national food security, the government should further refine land transfer mechanisms and socialized service support systems, strengthen the publicity, guidance, and technical training, and implement differentiated incentive measures. This will create a favorable institutional environment for large-scale agricultural operations, fully leverage the demonstration effect of large-scale farmers, effectively integrate smallholder farmers into modern agricultural development, and foster a virtuous cycle of mutual development.