Microplastics are widely persistent in agricultural ecosystems and may affect soil nitrous oxide (N2O) emissions. Nitrification inhibitor 3,4-dimethylpyrazole phosphate (DMPP) is applied to decelerate nitrification and reduce soil N2O emission. Nevertheless, the interactive effects of nitrification inhibitors and microplastics on soil N2O emissions have not been investigated. Sole DMPP, polyvinyl chloride (PVC), and polystyrene (PS) substantially reduced agricultural soil N2O emission rates by 25.93%, 69.04%, and 73.89%, respectively. Nevertheless, PVC and DMPP had antagonistic effects on the N2O emission rates. The observed reductions in N2O emissions could be attributed to variations in soil oxygen availability, electron transport system activities, and Firmicutes, nap, and GDH genes. Moreover, the DMPP, PVC, and PS alone or copresences significantly enhanced the soil ecosystem multifunctionality (EMF). The findings shed light on the role of microplastics in soil N2O emission, EMF, and the microbial community, expanding the understanding of microplastics' effects on agrochemical effectiveness.