In this work, we propose a facile fabrication method for C-doped zinc oxide (ZnO) submicron spheres using ionizable surface groups without an additional surface modification process after heat treatment. The synthetic method is comprised of diffusion of zinc precursors into pH-responsive polymer microspheres and a subsequent heat treatment step. After heat treatment at a certain temperature, the ionizable functional groups remaining on the surface of the C-doped ZnO submicron spheres resulted in improved dispersion stability of the spheres in the fluid colloidal system. Using the photocatalytic activity test, the relationship between dispersion stability and the photocatalytic property of the C-doped ZnO submicron spheres was investigated. As a result, the content of carbon atoms and the surface functional groups depended on the pH of the reaction medium.