He was educated at a Polish school in Tiflis and graduated from gymnasium in Warsaw. In 1915-1919, he served in the Polish Legions. He studied at the Faculty of Fine Arts at the USB in Vilnius. From 1932 to 1939, he worked in Paris as an official of the Polish Ministry of Foreign Affairs. During this time, he belonged to the Group of Parisian Polish Artists and presented his works in Paris in 1938 at the Salon des Tuileries and at the Salon d'Automne (Szczepińska-Tramer J., "In Search of Light, Shape and Colours"). During the war he was active in the Polish army and took part in the fighting at Narvik. He found himself in Scotland and England, inscribing himself "in the landscape of the English and international artistic community, above all in London and Edinburgh" (J. W. Sienkiewicz, "Anders' Artists").

In 1949 the artist emigrated to Canada and settled in Montreal. (Until 1965, he was Minister Plenipotentiary to President A. Zaleski in the Polish Government in Exile). He continued his artistic activities and was actively involved in the life of the Polish community. In 1950, he took part in the Exhibition of Polish Artists on Exile in Canada at the Montreal Museum of Fine Arts. He co-organised the exhibition "Neo-Canadians," in 1954, presenting the work of Polish artists. In the same year, Jastrzembski's works participated in an exhibition to celebrate the 3rd of May, organised by the Montreal Polish Congress, in the window of the Eaton department store. On the occasion of the 10th anniversary of the Polish-American Congress at McGill University, a Polish Art Exhibition was prepared. "Advice and guidance will be provided by the painter and friend of the university youth Octavian Jastrzębski. A catalogue of the exhibition is in print. The exhibition brings together paintings, drawings and sketches by Polish artists deported from Poland during the war and works already created in Canada. The exhibition is an excellent testimony to the level of culture and development of painting in the Polish community" ("Związkowiec", 1954).

The artist was a member of the Polish Decorative Club, founded in Montreal in 1955. The themes of Jastrzembski's works were landscape, portrait, still life and flowers. 'Portrait of Olga Boznańska' from 1938, included in the publication 'In Search of Light, Shape and Colour. Polish Artists Exhibiting at the Paris Salons 1884-1960' shows the influence of Cubism. The artist's works from the Canadian period are unknown.