In 1923 Sorge met with Russian scholar D. Riaznov who was looking to obtain original documents authored by Karl Marx. Sorge's uncle, Frederich Sorge, had previously served as Marx's personal secretary and Sorge was in possession of several of these documents. After providing these to Riaznov, Sorge was introduced by the scholar to a number of high ranking Russian intelligence officers.

Sorge and his wife soon traveled to Moscow where he met with Communist Party officials and received his official Communist Party membership card. After being assigned to the OMS division of the Orgburo, Sorge undertook numerous intelligence operations. His wife, unhappy with the time consumed by his new duties divorced him.

Began working for the GRU in 1930, serving in the Fourth Bureau under General Yan Karlovich Berzin. Sorge was sent to Shanghai in 1930 to help in the attempt to initiate a Communist revolution in China. He gathered intelligence about Chinese leader Chiang Kai-shek and his supporters. Posed as an agricultural researcher and was able to travel throughout China. Worked with underground Communist groups gathering information.

Was introduced to fellow aggent Agnes Smedey in late 1930. Smedley put Sorge in contact with her oyfriend, news correspodent Hotsumi Ozaki, from whom Sorge would receive intelligence information for several years. Sorge also worked with a friend of Ozaki's named Teikichi, also a correspondent, working for the Shanghai Weekly. Passed the information he gathered from these contacts and passed it on to another agent, radio operator Max Klausen. Was briefly involved with Soviet agent Ruth Kuczynski.