The effect of block copolymer and multiwalled carbon nanotubes (MWCNT) incorporation on the phase morphology and electrical properties of polypropylene(PP)/polystyrene blends(PS) were investigated. The nanocomposites were prepared by melt mixing in a batch mixer. The blend morphology was characterized using scanning electron microscopy (SEM). MWCNT localization and dispersion was studied by using transmission electron microscopy (TEM) and light microscopy. The electrical conductivity of 1.0 vol. % MWCNT filled PP:PS/70:30 blend increased 5 orders of magnitude with addition of 1.0 vol% diblock and triblock copolymers. Increasing copolymer concentration more than 1.0 vol.% does not provide further improvement in electrical properties. The improvement in conductivity was correlated to the copolymer/filler localization and the morphology development in the polymer blend system.