Livestock grazing strongly affects biodiversity and ecosystem functioning in grasslands. However, it remains unclear how different grazing impact multiple biodiversity, ecosystem multifunctionality (EMF), and their relationship with the interactions of grazing duration, livestock type and climatic factors. Here, we conducted a global synthesis from 104 published studies. Our results showed that light and moderate grazing improved multi-diversity, but heavy grazing significantly decreased multi-diversity and EMF. The grazing-induced decrease of EMF intensified with grazing duration, and the reduction of multi-diversity and EMF under intensive grazing was stronger in more arid climates. The response of EMF increased linearly with that of multi-diversity under all grazing intensities. Moreover, grazing intensity reduced EMF largely via decreasing multi-diversity, whereas a shift of livestock type from small to large size promoted EMF by increasing multi-diversity. This study provides first empirical evidence and new insights into the relationship between multi-diversity and EMF under grazing in global grasslands.