Copper(II) oxide (CuO), manganese dioxide (MnO2), and silver (Ag) nanoparticles were synthesized using Kalopanax pictus plant extract. The nanoparticle synthesis was monitored using UV-visible spectra. The occurrence of each peak at 368, 404, and 438 nm wavelength indicated the synthesis of CuO, MnO2, and Ag nanoparticles, respectively. The synthesized nanoparticles were characterized by X-ray photoelectron spectroscopy, energy dispersive X-ray spectroscopy, field emission scanning electron microscopy, and transmission electron microscopy. Catalytic potentials of the synthesized nanoparticles were compared to degrade two typical acidic and basic dyes (Congo red and Safranin O). The degradation ability of MnO2 nanoparticles against Congo red was higher than that of Ag and CuO nanoparticles. All three types of nanoparticles showed a similar degradation ability against Safranin O over 80%. This study demonstrates that biologically synthesized nanoparticles using Kalopanax pictus are good agents for degradation of dyes.