The main goal of this research was to study how enzymatic treatment of hemp and flax fibres affects their utilization as reinforcement in polypropylene composites. Enzymes are environmentally benign, can be reused, and require mild operating conditions. The central hypothesis of this study is that the removal of hemicellulose and pectic fractions would reduce surface polarity resulting in fibres better suited for thermoplastic owing the reduction of hydroxyl groups distributed on the fibres surface. As a result, hemicellulases, pectinases, and a laccase were investigated. The removal of hemicellulose and pectic components using xylanase (with and without cellulase) and polygalacturonase, respectively, resulted in improved thermal properties and water resistance. The removal of up to 25 % (wt) of natural fibre did not significantly compromise the mechanical properties of the composite materials. This environmentally benign approach could be tailored to pretreat other feedstocks and optimized to cleave a specific amount of fibres for different composite applications.