As an adolescent, he attended high school at Montreux and Lausanne in Switzerland, spending his vacations in Romania, especially in the Moldavia region.
He volunteered for service in World War I from 1917 to 1918, becoming the youngest second lieutenant in the Romanian Land Forces and taking part in military operations in the Carpathians.
Demobilized at Iași after the end of hostilities, he rambled across Moldavia with his friend Horia Teodoru; the two recorded their impressions in a series of drawings that was soon the subject of an exhibition.
In 1919, the friends left by ship for Marseilles and then went to Paris, where Cantacuzino met his father (still in the diplomatic service) after an absence of several years due to the war.
[1] In 1928, while in Paris and Vicenza, he wrote a study on the life and work of Andrea Palladio; in Italy, he had undertaken minute research into the Renaissance architect's buildings.
Prefaced with a letter by Georges Gromort to Cantacuzino, the book included sixty-four plates and a short introduction in which the author explained his architectural philosophy.
Gromort commented that the architects had conceived a Palladian palace with a strictly utilitarian purpose, likening the neoclassical building to a palazzo of Vicenza.
[1] Beginning in 1930, he began a sustained five-year period of architectural work in Romania, planning a number of important structures.
These included the Eforie ensemble, the Industria Aeronautică Română hangar in Brașov, Casa Radiodifuziunii in Bod, the Tețcani church and several villas.
He published Arcade, firide și lespezi in 1932; the book received strongly positive reviews from Mihail Sebastian and Perpessicius.
In addition to his radio work, Cantacuzino remained in the public eye through a series of columns on Romanian art and architecture published in Revista Fundațiilor Regale.
During the 1940 Vrancea earthquake, the Carlton Bloc collapsed, initially drawing the ire of the National Legionary State authorities against its architect, Cantacuzino.
[3] In the period immediately after the war, he continued his architectural activity, designing a number of villas as well as other projects, the most imposing of which is the Institute for Studies and Power Engineering building in Bucharest.
Cantacuzino was hired by the Metropolitan of Moldavia, but as he could not officially declare he had given work to the blacklisted architect, paid him a salary out of his personal funds.
[4] Cantacuzino's wife left for England in 1939 with the couple's son and daughter; due to the intervention of World War II and communism, none of them ever moved back to Romania or saw him again.
[8] Ion Mihai Cantacuzino, a distant relative, published a biography in French in 2011; this appeared in Romanian translation the following year as O viață în România.