The escalating challenges of food security, environmental degradation, and climate change have rekindled interest in the fundamental contributions of biodiversity to agricultural systems, particularly for organic farming. This review emphasizes the significant role of biodiversity on two key ecosystem functions: pest control and nutrient cycling. Biodiversity provides the foundation for pest management in organic systems that prohibit synthetic pesticides. Diverse plantings create a variety of habitats that facilitate colonization by natural enemies, which in turn can regulate pests across crop habitats within landscapes. Moreover, genetic diversity within crops increases disease resistance with respect to many pathogens, including viruses and bacteria, reducing dependence on inputs and fostering cost-effective economic and ecological stability. Biodiversity also forms the foundation for nutrient cycling via soil organisms that decompose composts and cycle soil nutrients for primary production. How botanical diversity enhances rapid decomposition remains unresolved but is likely due to a concomitant increase in decomposer biomass or microbial genetics preadapted to novel resources. Emerging research also directly links biodiversity with agricultural resilience by highlighting the importance of diverse primary producers (plants) facilitating diversity among the consumers (herbivores) as well as the potential positive implications this may have for biocontrol. Despite growing links between biodiversity and both pest control and nutrient cycling within agricultural systems we still lack access to information on mechanisms and management approaches that farmers can employ to increase or manipulate biodiversity within these specific agroecosystem processes. Furthermore economic constraints represent a major impediment hindering our ability to afford greater or even sufficient levels of desired diversity within crop fields or surrounding multi-functional landscapes.