As the field of 3D printing continues to enable the fabrication of biomedical materials and devices, there is increasing demand for the development of biocompatible functional materials with tailorable properties. Here, we utilized a desktop 3D printer to fabricate porous structures of electrically conductive polymer composites comprised of multiwalled carbon nanotubes (MWCNTs) in a matrix of polyhydroxybutyrate (PHB). PHB is a biocompatible, biodegradable, and piezoelectric polymer. The MWCNTs were melt-mixed in amounts from 0.25 to 5 wt % in PHB from two different suppliers with slightly different physical properties. The nanomaterial dispersion, morphology, electrical, thermal, and mechanical properties, and the crystallization behavior of both types of composites were investigated. A good dispersion at the macro- and microscale was observed in both types of composites. Electrical percolation threshold ranges of 0.25-0.5 wt % and 0.5-0.75 wt % were found for composites made with the two different types of PHB. The addition of MWCNTs resulted in an increase of Young's modulus and decrease of strain at break for both composites. The processability of the materials was demonstrated by 3D printing both stretchable meandering conductive traces and well-defined pore structure scaffolds. Biocompatibility tests were performed with MRC-5 cells and showed that the materials lack cytotoxicity. These results show the potential of these electrically conductive materials for use in biomedical electronic devices or as electro-active scaffolds for tissue regeneration applications, which require biocompatible, porous materials with microscaled architectures.