Conductive films that are both stretchable and flexible could have applications in electronic devices1,2, sensors3,4, actuators5 and speakers6. A substantial amount of research has been carried out on conductive polymer composites7, metal electrode-integrated rubber substrates8,9,10 and materials based on carbon nanotubes and graphene1,2,11,12,13. Here we present highly conductive, printable and stretchable hybrid composites composed of micrometre-sized silver flakes and multiwalled carbon nanotubes decorated with self-assembled silver nanoparticles. The nanotubes were used as one-dimensional, flexible and conductive scaffolds to construct effective electrical networks among the silver flakes. The nanocomposites, which included polyvinylidenefluoride copolymer, were created with a hot-rolling technique, and the maximum conductivities of the hybrid silver–nanotube composites were 5,710 S cm−1 at 0% strain and 20 S cm−1 at 140% strain, at which point the film ruptured. Three-dimensional percolation theory reveals that Poisson's ratio for the composite is a key parameter in determining how the conductivity changes upon stretching.