With the rapid development of electronic information technology, traditional metal conductive materials can no longer satisfy the needs of a wider industry. Poly(butylene succinate)/multiwalled carbon nanotubes (PBS/CNT) conductive polymer nanocomposites with varied CNT content were prepared by a HAAKE torque rheometer. The addition of CNT significantly improved the crystallization, viscoelasticity, and mechanical properties as well as thermal and electrical conductivity. Conductivity of the PBS/CNT nanocomposite with 5 wt.% CNT increased from 8.23×10− 15 S·m− 1 of pure PBS to 33.3 S·m− 1, an increase of 16 orders of magnitude. Moreover, the electrical percolation threshold φc of the PBS/CNT nanocomposites was 2.8 wt.% and the critical index was 1.56, showing that the conductive network structure was between 2D and 3D and 2D network structure dominated. To further improve the conductivity, microcellular foams were successfully fabricated by batch foaming with supercritical fluids (scCO2). The electrical conductivity of the PBS/CNT foam with 5 wt.% CNT reached 67.8 S·m− 1 and it was 104% higher than the corresponding solid nanocomposite.