In this work, we focus on exploring a new method to prepare conductive nanoporous polymeric materials, by simply incorporating multi-walled carbon nanotubes (MWCNTs) into melt-miscible poly(L-lactic acid)/poly(oxymethylene) (PLLA/POM) blends. The POM components in the ternary nanocomposites crystallize first to form “nano-hybrid shish-kebab (NHSK)” structures at a high temperature in the presence of MWCNTs, with the simultaneous exclusion of poorly crystallizable PLLA chains into the intra-NHSK regimes. The subsequent PLLA crystallization in the intra-NHSK regimes is also nucleated on the surface of MWCNTs and transforms the final crystal morphology into “ternary-hybrid shish-kebab (THSK)” superstructures. Therefore, a “binary-polymer-decoration” of MWCNTs, named “block-assembling”, is achieved. Such a novel “block-assembling” structure is further used to fabricate conductive nanoporous polymeric materials with a unique interposition structure of CNTs in the inner wall of the internal pores after the removal of the PLLA components in the ternary nanocomposites.