A polymerized toner is provided. The polymerized toner comprises a reactive anionic surfactant having at least one reactive functional group. The reactive anionic surfactant is added simultaneously with a dispersant to prepare an aqueous dispersion or is added within 2 hour after a polymerization reaction of a monomer mixture is initiated in an aqueous dispersion. This simultaneous or rapid addition allows the reactive anionic surfactant to be dispersed on the surface of the toner particles. The reactive anionic surfactant is located over the entire surface of the toner particles to increase the surface charge density of the toner, achieving good charge stability and excellent imaging characteristics.