Background Major changes in diets and food systems will be required to limit climate change and meet the Sustainable Development Goals, while providing healthy diets to a growing population. Among others, these changes include what foods are being produced and where, which has implications for the quarter of labourers currently employed in agriculture globally. We estimated the labour requirements for agricultural (primary) production associated with healthy and sustainable diets at global, regional, and national levels. Methods We constructed an inventory of agricultural labour requirements per food and region based on farm-level estimates and paired it with a set of diet and food-system scenarios. The scenarios included changes to a set of healthy and sustainable dietary patterns, including flexitarian, pescatarian, vegetarian, and vegan dietary patterns. We combined the inventory of labour requirements with a biophysical input–output model of the global food system to trace how changes in food consumption would affect changes in food production and the associated labour requirements for 20 food groups in 179 countries. Findings We found that transitions towards healthy and sustainable food systems could lead to substantial changes in the amount and distribution of agricultural labour. Compared with estimates of food demand in 2030 under a business-as-usual scenario, adopting more plant-based dietary patterns was associated with global reductions in labour requirements ranging from 5% for flexitarian and pescatarian diets to 22–28% for vegetarian and vegan diets. Reductions were strongest in countries currently dominated by livestock production, but a quarter to half of countries showed increased labour requirements to meet increased horticultural demand for fruits and vegetables. The changes in labour requirements were associated with global reductions in labour costs of 0·2–0·6% of gross domestic product annually. Interpretation Consistent strategies and political support will be needed to enable just transitions both into and out of agricultural labour.