Abstract: Plants have to face complex environmental challenges, including fluctuations in nutrient availability, biotic stresses, and abiotic stresses, throughout their entire life cycle. These environmental factors interact with each other. Phosphorus (P), as an essential macronutrient for plant growth and development, exhibits intricate interactions with biotic stress. In this review paper, we summarized the interactions between plant P nutrition and biotic stresses, elaborated on the underlying mechanisms of effects of biotic stresses on P homeostasis, as well as the molecular mechanisms underlying the role of P nutrition in biotic stress responses. Additionally, we discussed the role of phytohormones in these processes and proposed future research directions. P status affects plant responses to invasions by various pathogens, herbivores and other biological agents, though this is dependent on plant species and the kinds of infecting pathogens. The P nutritional status in plants can regulate biotic stress responses through phosphate signaling pathways. PHR1 and its homologous protein PHL1, the core transcription factors in phosphate signaling, play critical roles in regulating plant immunity and shaping the composition of rhizosphere microorganisms. Plant P levels can directly affect responses to biotic stresses through the phosphate starvation response (PSR) pathway. Plant hormones play pivotal roles in the trade-off between P nutrition and defense responses. Additionally, pathogenic microorganisms can influence the uptake, transport, and utilization of phosphate through multiple mechanisms. For instance, some fungal pathogens enhance the PSR in plants by releasing effector Nudix hydrolases to hydrolyze inositol pyrophosphates, thereby promoting P uptake and pathogen infection. Exploring the interaction mechanisms between plant P nutrition and biotic stresses will facilitate the synergistic improvement of nutrient use efficiency and resistance to pests and diseases in crops through genetic engineering, molecular breeding, and other approaches, ultimately promoting the green and sustainable development of agricultural ecosystems.