What is the contribution of the ‘Green Revolution’ to improvements in child health during the  century? We provide global scale estimates of this relationship by constructing a novel, spatially-precise indicator of modern crop variety (MV) diffusion and leveraging child-level data from over 600,000 children across 21,604 sampling locations in 37 developing countries between 1961–2000. Results indicate that the diffusion of MVs reduced infant mortality by 2.4–5.3 percentage points (from a baseline of 18%), with stronger effects for male infants and among poor households. The sizable contribution of agricultural technology to improved welfare should inform global food and development policy.