Organic farming has been proposed as a feasible way to reduce the environmental impacts of agriculture, provide better products to consumers, and improve farmers' income. How organic farmers are distributed worldwide, however, remains unknown. Using publicly accessible registries of organic crop farmers we mapped their distribution globally and related it to local socio-economic, climatic, and soil characteristics. We show that organic crop farmers are mostly present in areas with favorable socio-economic and climatic conditions, both globally but also within countries. Within developed countries, the locations of organic crop farmers often do not differ significantly from the locations of conventional crop farmers. In developing countries, there are, however, larger differences and organic crop farmers concentrate in the more accessible and developed regions. Our results suggest that crop farmers in poor areas may not have sufficient access to certification and markets. To promote the spread of organic farming, certification and other incentives could target farmers in areas with lower market access and higher levels of poverty which could improve value chains for organic products in these areas.