The rapid surge in water contamination is considered a significant global environmental challenge in the 21^st century, with various sectors like industries, hospitals, domestic sewage, agriculture, livestock, and land leachates contributing to this problem. Among the various pollutants, dyes stand out as the most prevalent organic contaminants, posing harmful effects on all living organisms. To assess the photocatalytic degradation of dyes like crystal violet and methylene blue, we have successfully synthesized cobalt oxide using an extract from the leaves of the Cestrum nocturnum plant, employing the co-precipitation method. We characterized the prepared CoO using FTIR and UV-visible spectroscopy, revealing their exceptional adsorption capabilities and promising performance in removing dyes from water. The bio-synthesized CoO exhibited a 69 % degradation for CV and an impressive 97 % degradation for MB.