By using a microfluidic device, we have prepared an elastomeric microfiber comprising natural rubber, carbon nanotubes (CNTs), and poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS). The combination of CNTs and PEDOT:PSS improved the linearity of the resistance change upon stretching as well as the conductivity of the microfibers by forming an efficient percolation network. Cellulose nanofiber, an eco-friendly nanomaterial with excellent physical properties such as high strength, lightweight, and solubility, interacts with the natural rubber mattress to firmly hold the structure of the matrix to improve mechanical strength. Natural rubber mattresses also interact with CNTs and as a result, they have a high toughness and can stretch up to 1200%.