Terrified that his theft had been exposed, he and his family hid in their apartment that night, ignoring several loud knocks on the door. He contacted his neighbor, a Canadian Air Force officer and explained his story to him. The officer helped him to hide his family and contacted the Royal Canadian Mounted Police. A few days later, four men crashed through the door of Gouzenko's apartment and ransacked it. The men were detained by the police who identified the as employees of the Soviet Embassy. When an inspector on the scene turned his head, the four men fled.

On September 8, 1945, the Soviet Embassy complained about their employees being detained and questioned, citing their diplomatic immunity. Embassy officials the demanded that Gouzenko, whom they described as a criminal, be arrested and turned over to them. They claimed that he had stolen funds from the Embassy and wanted to return him to Moscow for prosecution.

Gouzenko was in the custody of the Royal Mounted Canadian Police and had provided them with a number of documents, the quality of which were compelling enough for them to realize that he was genuine about his desire to defect. The papers described a world-wide spy operation, set into place by the Soviet Union and operating throughout the world. Under protective custody, Gouzenko continued to expound upon his claims. He exposed numerous Soviet agents (listed on index cards from the Embassy) and provided them with notes from the casebook of Soviet spymaster Colonel Nicolai Zabotin. Canadian officials quickly thereafter shared these revelations with the U.S. and British governments.

Because he was exposed by Gouzenko, Colonel Zabotin was recalled to Moscow and was sentenced to four years of hard labor for allowing a disgruntled employee to compromise the entire Soviet spy apparatus. Appeared several times on Canadian television wearing a hood over his head in order to conceal his identity. Penned his autobiography (titled This Was My Choice) in 1948.

Died in 1982.