Global food security requires increased crop productivity to meet escalating demand1–3. Current food production systems are heavily dependent on synthetic inputs that threaten the environment and human well-being 2,4,5. Biodiversity, for instance, is key to the provision of ecosystem services such as pest control6,7, but is eroded in conventional agricultural systems. Yet the conservation and reinstatement of biodiversity is challenging 5,8,9, and it remains unclear whether the promotion of biodiversity can reduce reliance on inputs without penalizing yields on a regional scale. Here we present results from multi-site field studies replicated in Thailand, China and Vietnam over a period of four years, in which we grew nectar-producing plants around rice fields, and monitored levels of pest infestation, insecticide use and yields. Compiling the data from all sites, we report that this inexpensive intervention significantly reduced populations of two key pests, reduced insecticide applications by 70%, increased grain yields by 5% and delivered an economic advantage of 7.5%. Additional field studies showed that predators and parasitoids of the main rice pests, together with detritivores, were more abundant in the presence of nectar-producing plants. We conclude that a simple diversification approach, in this case the growth of nectar-producing plants, can contribute to the ecological intensification of agricultural systems.