The valorization of plant wastes allows access to renewable carbon feedstocks without increasing the demand for plant biomass production. Plant wastes are the non-edible residues and waste streams from agriculture, agroindustry and forestry. The chemical diversity and recalcitrance to degradation of such wastes challenge our ability to transform and valorize these resources into value-added compounds. Fungi that thrive on plant tissues have gained a huge diversity of enzymatic toolkits for the finely-tuned degradation of glycan and lignin polymers. Our knowledge on the enzymatic systems developed by fungi now guides innovations for plant waste bioprocessing. Here, we provide an overview of the most recent findings in the hydrolytic and oxidative systems used by fungi for the degradation of recalcitrant plant polymers. We present recent promising success in applying fungal enzymes or fungal fermentations on plant wastes, and discuss the forthcoming developments that could reinforce fungal biotechnology entering a variety of industrial applications.