A black-odor river water quality improvement project was conducted in Jiangmen City, Guangdong Province, China. A combination of sewage interception and source control, aeration and oxygenation, a biological contact oxidation tank, and the construction of aquatic ecosystems was used. To manage the irregular discharge of domestic sewage and high ammonia nitrogen content of the river, the traditional biological contact oxidation process was improved. A biological contact oxidation tank was constructed. High-efficiency ammonia nitrogen bacteriological agents were injected into the river for the management of river sewage. After four months of operation, this innovative process was stable and efficient with respect to the degradation of river pollutants. The transparency and dissolved oxygen content increased from 8.8 to 69.5 cm and 1.5 to 6.4 mg L⁻¹, respectively. The ammonia nitrogen, total phosphorus, and dichromate oxidizability concentrations decreased from 6.4 to 1.6, 0.67 to 0.30, and 101 to 31.7 mg L⁻¹, respectively. The black odor was removed from the river and the water quality indicators met the class V surface water standards after the project was completed. The new methodology is effective with respect to the management of black-odor waterbodies. The results of this study provide a reference for the treatment of black-odor rivers in cities.