The current global trend towards sustainability has generated a fresh enthusiasm for the conversion of waste materials into useful resources across all industries. Within the construction industry, conventional cement-based materials have played a crucial role in the advancement of infrastructure. However, there is a growing recognition of the pressing requirement for more environmentally sustainable alternatives. Within this particular framework, the reclamation and repurposing of Waste Fishing Trawl (WFT) fibers made from polyethylene and Waste Fishing Rope (WFR) fibers made from polypropylene emerge as a noteworthy strategy that combines environmental awareness with innovative manufacturing techniques. This study investigates the impact of polyethylene-based WFT fibers and polypropylene-based WFR fibers on the mechanical characteristics of Cementitious Composites (CC). The study sheds light on the difference in the effects of the two types of fibers on the mechanical properties of the CC. Significantly, the incorporation of these fibers elicits discernible alterations in the mechanical characteristics. The mechanical properties, particularly flexural and tensile strength, demonstrate a notable enhancement, but the compressive strength remains nearly unchanged. Additionally, an intriguing fact emerges about the porosity of the cement-based material. The present work provides evidence of an observed increase in porosity as a consequence of the inclusion of WFT and WFR fibers. When discussing the fresh state properties, the incorporation of both types of fibers led to a reduction in the workability of the cementitious matrix.