Tri-block copolymer styrene–butadiene–styrene (SBS) composites with different butadiene/styrene ratios and multi-walled carbon nanotubes (MWCNTs) can be used for the development of electro-mechanical sensors for large strains applications. Extruded CNT/SBS composites show percolation thresholds around 5 wt%, electro-mechanical properties with high sensibility at larger strain and the gauge factor reach values up to 30 at strains of 20%. The butadiene/styrene ratio has influence in the mechanical and electro-mechanical properties. In one hand, the increase of the styrene content in copoly-mer increasing initial mechanical modulus, on the other hand, the increase of the butadiene content leads to larger maximum deformations and higher electro-mechanical sensibility for strains up to 20%. Further, applied initial pre-stress increases the electro-mechanical sensibility of the composites.