Herein, the electrorheological (ER) properties of highly dispersion-stable, biocompatible and biodegradable chitosan derivative dispersed ER suspensions are explored. Electro-mechanical responses of the ER suspensions are enhanced with fixed spacers (amide and ester groups) and various functional groups (acid series and their complex forms with urea). A noteworthy result is that the shear stress of urea complexed chitosan acid dispersed suspensions was higher than before doping the urea molecule. However, urea complexed chitosan phosphate and sulphate showed a decreased tendency of shear stress due to too high conductivity at the high temperature. In the dispersion stability test, the chitosan dispersed suspensions showed high dispersion stability for long times. The study of the influence of dipolar molecules on the ER properties of the chitosan derivative dispersed suspensions under an electric field shows how to enhance the ER responses easily just by doping molecules.