["Agribusiness, EarlyView. ", "\nABSTRACT\nEnsuring food security requires understanding how maize yield is sustained where mechanization cannot fully substitute for labor. In such settings, labor may contribute not only as a quantity input but also through crop management and field‐level adjustment. Using a nationwide household panel from China's Rural Fixed Observation Points Survey for 2012–2021, this paper examines whether higher labor density is associated with higher maize yield per mu. We estimate household fixed‐effects models and complement them with multiple robustness checks and an instrumental‐variables strategy. The results show that labor density is positively and robustly associated with maize yield per mu. Additional analyses indicate that this relationship is driven more strongly by family labor than by hired labor and is associated with smaller within‐village land‐allocation mismatch, as well as lower land fragmentation. The positive association is weaker for households with better mechanization conditions, stronger in hilly and mountainous areas than in plains, and remains positive but smaller in households with higher aging rates. Taken together, the findings suggest that the yield‐related role of labor depends on the limits of capital–labor substitution. Where mechanization remains incomplete or uneven, labor–land complementarity provides a second‐best but economically meaningful pathway for sustaining maize yield."]