<p>Currently, additive manufacturing (AM) of composite structures is finding increasing use because it allows the fabrication of tailored lightweight structures. The introduction of bio-based polymers and fibers enables the possibility to produce structures with good mechanical properties and low environmental impact. Fused filament fabrication (FFF) is among the less energy-consuming AM techniques. Nevertheless, biocomposites printed by FFF still are far from being investigated from both sustainability and mechanical performance perspectives. This work aims to fill this gap of knowledge. In particular, it aims to jointly evaluate the environmental impact and mechanical properties of PLA specimens printed by FFF using filaments filled with different percentages, 2% and 10%, of basalt powders and short hemp fibers, by comparing the selection of two deposition angle, 0° and 90°. Pure PLA specimens have also been printed and assessed in comparison to the biocomposites. A cradle-to-gate life cycle assessment (LCA) has been performed using primary experimental data, to highlight the potential advantages in terms of sustainability offered by the use of natural fibers in the FFF of composite materials. The results of this work demonstrate the potentialities offered by the natural fibers by increasing the mechanical properties under certain conditions while reducing the environmental impact.</p>