Epoxies have a weak fracture toughness; hence it is essential to enhance this property. This study revealed that interleaving 110-micron thickness of chopped carbon fibers and Poly-amide 66 nano-mats in Glass Fiber Reinforced Plastic laminates increased mode-I fracture toughness by 35% and 112%, respectively. Acoustic emission data illustrated that damage mechanisms initiate at further load-point displacement in modified samples. By classifying different failure types using a hierarchical clustering model, it was observed that the dominant damage mechanisms in reference, chopped carbon and nanomodified samples are matrix cracking, fiber breakage, and matrix cracking in order. Moreover, nanomodified samples’ cumulative released energy was 83% less than the reference and chopped carbon. Different damage mechanisms were validated by scanning electron microscope observations.