The use of fossil fuels as a source of energy is becoming less desirable and sustainable due to finite natural resources and current environmental conditions. Research of renewable materials such as bioplastics is of importance in order to develop materials with similar or better mechanical properties as conventional plastics. Fused filament fabrication (FFF) is an additive manufacturing technology that offers a great promise to various industries including biomedical and automotive due to its ability to prototype and manufacture objects with custom and complex geometries. Poly(3-hydroxybutyric-co-3-hydroxyvalerate) (PHBV) is a biopolymer of interest due to its excellent biodegradable and biocompatible properties, however, its use in FFF has been limited due to its poor thermal stability such as having a narrow window between the thermal degradation and melting temperature. In this study, a suitable methodology for the 3D printability of PHBV via FFF was achieved by incorporating poly(lactic acid) (PLA) and a chain extender (CE) agent. Material properties including thermal, viscoelastic, mechanical and morphological were successfully correlated to assess the performance PHBV:PLA:CE based blends. Furthermore, enhancement of tensile and flexural strength, 12% and 23%, respectively, were achieved via process engineering by selecting appropriate 3D printing parameters including printing temperature, bed temperature, printing speed, layer thickness, raster design and infill density. This study reveals that proper diffusion-based fusion between layers is a critical component of 3D printing bioplastics in FFF and that design customization is required to achieve an optimal mechanical performance.