Polymers derived from biological sources are attractive materials from an environmental perspective. Like most polymers, their properties may be modified through the inclusion of micro- and nanoscaled fillers. Polyhydroxybutyrate (PHB) is a biopolymer that is both produced and enzymatically-degraded by bacteria. This material has excellent biocompatibility and stability in the body, and conductive PHB-based composites could be used in a variety biomedical applications, including tissue engineering, biosensors, and neural interfaces. In general, conductivity may be imparted to (insulating) polymers through the introduction of conducting fillers, such as carbon nanotubes (CNTs). While a few solution-processed PHB-CNT composites have been described in the literature, conductivity has not been demonstrated. In this contribution, PHB-CNT composites are formed by melt-mixing PHB with multiwalled CNTs. The morphology of the resulting material is explored by scanning electron microscopy (SEM), and well-distributed bundles of CNTs are observed within the polymer matrix. The CNT macrodispersion in the composites was characterized by transmission light microscopy showing some remaining CNT agglomerates. Despite this, a relatively low percolation threshold (~ 0.5 wt%) is achieved,with volume resistivity of 6 Ω∙cm at 5 wt% loading. Data describing the thermal and mechanical properties of the composites as a function of CNT loading will also be presented.