Microplastics and nanoplastics (MPs/NPs) are posing emerging potential threats to global ecosystems and human health. Recently, the individual effects of MPs/NPs and combined effects of MPs/NPs-coexisting pollutants on soil–terrestrial plant systems have attracted increasing attention. Based on the latest research progress, this review firstly summarized the sources of MPs/NPs and the interaction between MPs/NPs and coexisting pollutants in soil environment, and then systematically induced their multilevel impacts on soil properties and terrestrial plants. Soil and agroecosystem are major long-term sinks of primary and secondary MPs/NPs, with extensive sources. MPs/NPs exhibit universal adsorption capacities and can further serve as the vectors for varied heavy metal, organic and biological contaminants. Generally, MPs/NPs and the combination with coexisting contaminants may affect soil physical, chemical and microbiological properties, soil structure and functions, while the specific impacts and degree depend on MP/NP characteristics including polymer type, size, shape, concentration and degradability. Increasing evidence confirmed the uptake and translocation of MPs/NPs in terrestrial plants and proved their influence on growth performance, metabolism and physiological toxicity, as well as cytotoxicity and genotoxicity. The specific effects vary as a function of MP/NPs properties, plant species and environmental conditions. The joint effects of MPs/NPs and coexisting pollutants are complex, and synergistic, antagonism and neutralization effects have been reported at different circumstances. Further comprehensive and in-depth studies are urgently needed to fulfill the current knowledge gaps, especially the deficiency in the inherent mechanisms.