Rhadinosa nigrocyanea is a species of beetle of the family Chrysomelidae. It is found in China (Anhui, Zhejiang, Fujian, Hainan, Jiangxi, Jiangsu, Guangdong, Manchuria, Xinjiang, Yunnan), Japan, Korea and Russia (Siberia).
The recorded host plants for this species are Digitaria glabra, Oryza sativa, Miscanthus and Arundinella species.