Multifunctional materials possess several desirable attributes such as improved thermal, mechanical, electrical, chemical properties etc. Several research studies have highlighted the benefits of utilizing nanoparticles, including carbon nanotubes (CNT), dispersed in a polymer matrix. Such nanocomposites possess improved mechanical, electrical and thermal properties, and have numerous applications as sensors, electrodes, actuators, electronic packaging, adhesives etc. The focus of this study is porous multifunctional elastomer-CNT nanocomposites. A thermoplastic polyurethane (TPU) was chosen as an elastomeric matrix, which was reinforced with multiwall carbon nanotubes (up to 10 wt%) by high shear twin screw extrusion mixing. Porosity was introduced to the composites through the phase separation of a single TPU-CO2 solution. The addition of MWNT to TPU had a significant effect on the composite’s thermal properties. Increases in glass transition and crystallization temperature were observed with the addition of 6 wt% MWNT – suggesting that MWNT were finely dispersed in the composites such that they were affecting polymer chain mobility and acting as fine-sized nucleation sites, respectively. Significant improvements were also observed in the electrical conductivity of the nanocomposites (10-3 S/cm with 10 wt% MWNT). Addition of MWNT in TPU resulted in a significantly finer porous structure, albeit at the expense of volume expansion. Also, a porous structure resulted in slight deterioration of the electrical conductivity. The piezoresistance of the nanocomposites was analyzed under quasi-static compression. Piezoresistance was exhibited by the TPU-MWNT composites and porous composites. The solid composites had a non-linear response whereas the porous composites displayed a gradual two-stage linear response. The gradual decrease of resistance in the porous composites during the first stage is linked to the internal deformation of the cellular structure.