Piezoresistivity in conductive polymer nanocomposites occurs because of the disturbance of particle networks in the polymer matrix. The piezoresistance effect becomes more prominent if the matrix material is compliant making these materials attractive for applications that require flexible force and displacement sensors such as e‐textiles and biomechanical measurement devices. The objective of this work is to report on the development of conductive polymer nanocomposites for use in flexible sensors and electrode applications. Electrically conductive and piezoresistive nanocomposites based on Multiwall Carbon Nanotubes combined with either Polyethylene (PE), Thermoplastic Polyurethane (TPU) and Polyvinylidene Fluoride (PVDF) were fabricated using a scalable melt compounding process. Particular attention was given to elucidating the role of matrix and filler materials, plastic deformation and porosity on the electrical conduction and piezoresistance. These effects were parametrically investigated through characterizing the morphology, electrical properties, rheological properties, and piezoresistivity of the polymer nanocomposites. The electrical and rheological behavior of the nanocomposites was modeled by the percolation‐power law. Furthermore, a model was developed to describe the piezoresistance behavior during plastic deformation in relation to the stress and filler concentration.