Rivett-Carnac did not enjoy school, and during World War I loaned money off a friend to learn to drive so that he could join the British Red Cross as an ambulance driver.
Here Rivett-Carnac was in charge of the Assam Sawmills and Timber Company forest operations for the Tezpur area of India.
A few months later, due to his poor health he was sent to work at the head office in Calcutta where medical facilities were more readily available.
He spent many years working in the North of Canada, and he steadily rose through the ranks to become the 11th Commissioner of the force, a post he held from April 1, 1959 to March 31, 1960.
In 1945 while Rivett-Carnac was in charge of Intelligence at headquarters, he was heavily involved in the famous Igor Gouzenko case.