Biomass high-temperature soy meal (HSM)-based adhesives are gaining significant attention in the green household industry. However, the low initial adhesion and poor bonding performances have limited their applications in actual production. In this study, a stable waterborne epoxy emulsion (WEU) crosslinker and polyethylenimine (PEI) toughener were synergistically used to modify the HSM matrix owing to their regulated covalent interactions and branched chemistry. The WEU was prepared using a synthetic emulsifier that featured flexible polyether and alternating amine group blocks, providing numerous hydrogen bond sites and a toughened entangled network. PEI, with a unique spatial structure, was introduced to facilitate the noncovalent interactions, and also acted as a curing agent under thermo-curing. The synthesized adhesives exhibited excellent cold-pressing bonding strength at 0.99 MPa, which is sufficient to meet actual needs. Under certain pressure and thermal conditions, covalent bonds facilitated the formation of the crosslinking network. The resulting cured adhesive exhibited improved toughness, which was attributed to the branched and multiple noncovalent energy dissipation network. The HSM15-P7 adhesive exhibited outstanding wet shear strength, which increased by 3675 % compared with that of the unmodified HSM adhesives. This HSM15-P7 adhesive exhibited outstanding results compared with other reported biomass wood adhesives. This study provides a facile and comprehensible method for developing other bioresources for high-value industry products with high performances.