With unique physicochemical properties, nanomaterials offer new pathways for precisely regulating the plant rhizosphere environment and advancing sustainable agriculture. This review synthesizes 115 studies published between 2016 and 2026, focusing on how nanomaterials reshape the “microbe–soil–plant” ternary interaction network through multiple mechanisms, including the modulation of rhizosphere microbial functions, the driving of soil elemental cycles, and the regulation of root physiological and molecular responses. We also highlight the pronounced disconnect between experimental doses and environmentally relevant concentrations, and emphasize the need for field-scale validation. Further in-depth research is required to elucidate the interaction mechanisms and environmental behaviors at multiple rhizosphere interfaces, advance the green application of nanomaterials, and ultimately facilitate the construction of a precise, safe, and sustainable nano-agricultural technology system.