At a very young age, he expressed an interest in music, mathematics and drawing, and by the time he was an adolescent, he had already started publishing cartoons in newspapers and magazines. After attending classes at the National Technical University department of Civil Engineering for two years (1897-1899) and having taken drawing courses with Nikiforos Lytras (1899), he relocated to Paris in 1900 and stayed there for the greatest part of his life, occasionally travelling to various countries around Europe and to Greece. He studied at the School of Fine Arts with Fernand Cormon until 1902. From 1901 to 1912 he worked with many well-known humor magazines, such as Frou-Frou, Le Rire, Le Sourire, L'Assiette au Beurre, etc. , publishing cartoons and drawings.
It appears that his systematic interest for engraving manifested during a trip he took to Germany (1907-1909) and, in 1918, he began illustrating books – an activity that covers a substantial part of his artistic creation, comprising over one hundred books, albums, calendars and artistic editions. From 1930 onwards, he stopped painting and devoted himself almost exclusively to engraving/printmaking. Having acquired the French citizenship, he taught at the Académie André Lhote (1925-1928), at his own studio (1930-1937) tutoring Greek artists studying in Paris, and at the School of Fine Arts (1945-1952). In 1945, he was elected member of the French Academy and, in 1950, corresponding member of the Academy of Athens.
Demonstrating a prolific exhibition activity, both in France and in other countries, he presented his first solo show in Paris in 1922, with a prologue by Andre Malraux. He participated in several Paris Salons and, from 1920 to 1926, he co-exhibited with some of the most prominent artists of the time, such as Picasso, Matisse, Braque, Chagall and Derain, the latter also being a close friend of his. In 1991, his work was presented in a retrospective exhibition at the Museum of Contemporary Art - Basil & Elise Goulandris Foundation in Andros.
Dimitrios Galanis was one of the most significant engravers of the first half of the 20th century in Europe and a pioneer of modern Greek engraving, influencing his peers both through his work and through his teaching. Conversant with all techniques and extremely skillful, he revamped the traditional ways of engraving. His oeuvre comprises a wide variety of themes (mythological and idyllic scenes, landscapes, nudes and still lifes), the earlier ones manifesting influences from Cézanne and the movements of cubism and fauvism, while the later ones demonstrating a personal style based on the principles of the classical tradition.