Johnson Wu was born in Vladivostok. He was a son of Knime Wu, compradore of Bryner & Co. in Vladivostok.
Johnson Wu received his early education in his native town, Chungsan District, Kwangtung, China. Then he attended Soochowand Fu-tan Universities and later was graduated from the Comparative Law School of China, Shanghai, where he studied for three years. He received the degree of L.L.B (Bachelor of Laws) in 1926.
Johnson Wu has been engaged in legal practice in Shanghai from 1926. He was a member of the Shanghai Chinese Bar Association and the author of "Interpretation of the Chinese Criminal Code".