Sustainable intensification (SI) has been promoted within smallholder farming systems to improve agricultural productivity and reduce negative environmental externalities associated with agri-food systems. However, existing studies are concentrated towards the productivity effects of SI and input use efficiency impacts of SI are scant. This study assesses the impact of early sowing of wheat on productivity, nitrogen, phosphorus, potash, and combined fertilizer use efficiency in the eastern Indo-Gangetic Plains. We use the two-stage least squares instrumental variable approach to control the potential endogeneity that arises from both observed and unobserved sources of heterogeneity. We find that early sowing improves all resource use efficiency measures, as well as productivity. However, these impacts are unevenly distributed. Early sowing of wheat on large farms and farms applying doses of fertilizers exceeding the state recommendations are weakly associated with productivity and fertilizer use efficiency. Our findings suggest that while SI has potential to boost wheat productivity and fertilizer use efficiency, significant policy initiatives are required to minimize the over-application of fertilizers and mitigate the negative environmental externalities associated with agri-food systems in India.