The present disclosure relates to a process for preparing carbon fibers. The process involves blending a carbon nano-material with a carbon material to obtain a homogenous blend, heating the homogenous blend to obtain mesophase pitch having particles with reduced mesophase sphere size followed by spinning the mesophase pitch to obtain the pitch fibers. The pitch fibers are then carbonized to obtain the carbon fibers. The carbon fibers prepared by the process of the present disclosure have improved tensile properties as compared to the conventional pitch based carbon fibers.