Dyes are toxic and considered to be extremely hazardous to natural environments. Hence, adsorbents to remove dyes from contaminated water are needed. To develop adsorbents with a high adsorption capacity for different dyes, easy separation, and low cost, a novel dye adsorbent was prepared by activating fly ash with NaOH. The adsorbent morphology, structure, and specific surface area were characterized using scanning electron microscopy, X-ray powder diffraction, and surface area measurements using N2 adsorption-desorption. The adsorption abilities of the synthesized adsorbents were examined based on methylene blue and acid fuchsin adsorption from water. The capabilities of the adsorbents as a function of adsorbent use, dye type, dye concentration, time, and pH were investigated and compared. The results for methylene blue and acid fuchsin adsorption were modeled using pseudo-second order kinetics and the Langmuir adsorption isotherm, respectively. These modified adsorbents synthesized from fly ash may provide a promising solution to purify dye-contaminated waste water with the advantages of high efficiency and low cost.