This feature article reviews recent research on the fabrication of magnetic polymeric composite particles as well as their special applications as magnetorheological (MR) fluids. MR materials are a class of smart particles that can form chain-like structures when dispersed in a non-magnetic medium under an applied magnetic field. A range of methodologies for their fabrication, such as in situ polymerization and solvent casting, have been introduced to prepare micron-sized magnetic composite particles with polymers followed by a demonstration of their corresponding morphologies as well as their magnetic and MR properties. Both the magnetic properties of the particle and the MR performance of the MR fluid are strongly influenced by the incorporation of polymers including the synthesis method and mass ratio.