This work investigated two manufacturing methods, film stacking and powder impregnation, to fabricate plain-weave polymer-fiber-reinforced polymers (PFRPs) using UHMWPE fibers embedded in an HDPE matrix as an example. The powder-impregnation method has the potential to fabricate high-performance PFRPs but has been less explored in the literature compared to the prevalent film stacking method. By comparing the mechanical and morphological behaviors of the PFRPs with the same fiber volume fraction ( \({V}_{f}=\) 30%) fabricated using the two methods, it was shown that the powder-impregnated PFRPs have roughly 20% higher tensile strength and final failure strain compared to the film-stacked PFRPs. This can be attributed to better interfacial diffusion at the fiber–matrix interface, as well as the infiltration of the HDPE powder into the UHMWPE fiber tows for enhanced splitting resistance. This work is important for the further development of optimized manufacturing methods for the fabrication of high-performance PFRPs with various polymer fibers in general.