The development of formaldehyde-free plywood bio-adhesives is becoming a hot research topic. This contribution reports, for the first time, formaldehyde-free plywood bio-derived adhesives using hydrochar from bamboo powder, which has no nutritional ingredients, to address the poor anti-mildew properties of this material. The highest wet shear strength of bio-adhesives (BD-BP-APP) was 0.93 MPa, which meets the Chinese national standard GB/T 9846–2015 (≥0.7 MPa). Deep carbonization decreased the number of active functional groups on the surface of the hydrochar, reducing wet shear strength. The formation of covalent bonds was a key factor in improving wet shear strength during hot-pressing treatment. © 2024 Elsevier B.V., All rights reserved.