Conventional herbicide formulations suffer from serious problems such as easy drift, run‐off and scouring into the environment, which pose enormous threats to human health and environmental safety. Herein, an innovative strategy is proposed to prepare oil‐in‐water nanoemulsions with long‐term stability, enhanced droplet deposition, and improved nanoherbicide adhesion via steerable interfacial assembly of 1D amyloid‐like protein nanocomposites. Bovine serum albumin (BSA) undergoes rapid amyloid‐like aggregation upon reduction of its disulfide bond. The resulting phase‐transitioned BSA (PTB) oligomers instantly self‐assemble on the surface of cellulose nanofibers (CNF) to form the 1D PTB/CNF nanocomposites, which greatly expands the parameter space for interfacial assembly of amyloid‐like proteins. The PTB/CNF nanocomposites exhibit excellent interfacial activity, enabling spontaneous adsorption at the oil‐water interface to stabilize nanoemulsion. The excess PTB/CNF nanocomposites would also self‐assemble at the air‐aqueous interface upon spraying, resulting in efficient droplet deposition on (super)hydrophobic leaves. The deposited nanoherbicides show excellent resistance to wind/rain corrosion due to the robust amyloid‐mediated adhesion, with a retention rate of more than 80% after severe scouring. Consequently, herbicide applications can be reduced by at least 30% compared to commercial emulsifiable concentrates, showing greater herbicidal efficiency. This study provides novel insights and approaches to promote sustainable agricultural development.