Information about the global structure of agriculture and nutrient production and its diversity is essential to improve understanding of food production patterns, agricultural livelihoods, and food chains and their linkages to land use and their associated ecosystems services. We used existing spatially-explicit global datasets to estimate the production levels of crops, livestock, and aquaculture and fish products. We also estimated the production of vitamin A, vitamin B12, folate, iron, zinc, calcium, calories and protein. Furthermore, we estimated the relative contribution of farms of different sizes to the production of different agricultural commodities and associated nutrients, as well as how the diversity of food production, based on the number of different products grown per geographic pixel and distribution of products within this pixel (Shannon diversity index [H]), changes with different farm sizes. Globally, small and medium farms (≤50 ha) produce 51–77% of nearly all commodities and nutrients examined here. However, important regional differences exist. Large farms (>50 ha) dominate production in North America, South America, and Australia and New Zealand. By contrast, small farms (≤20 ha) produce more than 75% of most food commodities in sub-Saharan Africa, south-east Asia, south Asia and China. The majority of vegetables (81%), roots and tubers (72%), pulses (67%), fruits (66%), fish and livestock products (60%) and cereals (56%) are produced in diverse landscapes (H>1·5). Our results show that farm size and diversity of agricultural production vary substantially across regions and are key structural determinants of food and nutrient production that need to be considered in plans to meet social, economic and environmental targets. At the global level, both small and large farms have key roles in food and nutrition security. This analysis is crucial to design interventions that might be appropriately targeted to promote healthy diets and ecosystems in the face of population growth, urbanisation and climate change.