Charles Leirens was a musician, working in Ghent and Brussels, who in 1928 became director of the Palais des Beaux Arts in Brussels. In 1933, after he was forced to leave the Palais des Beaux Arts, he created the Maison d’Art as a centre for concerts, lectures and exhibitions and also founded the Revue Internationale de la Musique magazine. During his time as its editor he begun photographing artists, musicians and writers, developing a career as a photographer. In 1936 he published his first photobook, 20 Portraits d’Artistes, which included images of André Gide, André Malraux and Constant Permerke.

An invitation from the New School for Social Research to give a course in photography and musicology probably helped Charles Leirens to emigrate to New York in 1941.
Leirens was one of a number of other photographers on one of the last passenger ships to sail to the U.S. With him on board of the S.S. Winnipeg were Josef Breitenbach, Ylla, Ilse Bing, Fred Stein and Yolla Nichlas. The émigré photographer Fritz Neugass later wrote a record of their emigration in an article (Neugass 1951). When the S. S. Winnipeg encountered problems on the voyage the photographers and the rest of the refugees were required to put up in Port of Spain (Trinidad), where they were placed in a internment camp. As Leirens was an ally he was allowed to live in a hotel, where he ended up staying for eleven months after his visa expired and had to be renewed. However, he held his first photographic exhibition in Trinidad during his stay.

After his arrival in New York in 1941 or 1942, Charles Leirens started work with the Belgian Government Information Center, offering courses in music and photography. With the help of the Center he was also able to publish two books during the 1940s: Belgian Music (1943) and Belgian Folklore (1947). Besides this work, in 1942 he began his ten-year career at the New School for Social Research. From 1942 to 1951 he gave a number of courses in music: in 1942/43 “Intelligent Listening for the Untrained Music Lover” and “Bach and His Time”; in 1943/44 “Intelligent Listening for the Untrained Music Lover” and “Music in France from 1875–1914”, in 1944/45 “Music for the Untrained Music Lover”, in 1945/46 “The Intellectual Side of Music”, in 1946/47 “Musical Form”, in 1947/48 “The Fuge and the Sonata”, in 1948/49 “The Sixteen Quartets of Beethoven”, in 1949/50 “The Great Instrumental Forms as Exemplified in the Piano Sonatas and the Quartets Of Beethoven” and finally in 1950/51 “Bela Bartok”. His teaching career in the field of photography began in 1947 with his “Portraiture with the Miniature Camera” course. The year following year, until 1951, he gave the “Photography with the Miniature Camera” course and in 1948 and 1949 “Introductory Course in Photography”. Although he re-emigrated to Europe in 1952, Charles Leirens replaced Josef Breitenbach’s course for the autumn semester in 1952 with the title “From a Photographer’s Experience: Some Technique and Subject Matters”. This was his last course at the New School for Social Research. Other émigrés giving lessons in photography and offering photojournalism courses were Lisette Model, Marion Palfi, Kurt Safranski, Alexey Brodovitch and Tim Gidal. The émigrés Fred Stein and Werner Wolff also frequented the New School, showing their commissioned work for the Black Star photo agency, and the German émigré Erika Stone was a student there.

Charles Leiren’s photographs were shown at quite a few exhibitions in New York City during the 1940s. From 11 to 23 October, 1943, the Photographic Portraits of Prominent Europeans by Charles Leirens exhibition ran under the auspices of the Belgian Information Center at the Bignou Gallery at 32 East 57th Street (Anonymous, 1943). The Bignou Gallery was the New York branch of the former Bignou Gallery in Paris, owned by Étienne Bignou, which was closed in 1933. The gallery, which specialised in French and American painting, reopened in 1935 in the gallery district of Manhattan. In 1946 a portrait of Marc Chagall by Charles Leirens was presented at an exhibition on Marc Chagall at the Museum of Modern Art, with an enlarged print of it featured on the museum wall. In connection with MoMa's Marc Chagall exhibition, the émigré photographer Lotte Jacobi photographed the painter. Besides Lotte Jacobi, the émigré photographers Hermann Landshoff, Fred Stein, Lilly Joss Reich, Ellen Auerbach and Rudy Burckhardt also captured the artistic émigré scene in 1940s' New York.

After World War II Charles Leirens travelled to Morocco in the summer of 1948. The photographs he took there were exhibited a year later at the New School for Social Research, from 27 January to 18 February, 1949. In the post-war period Charles Leirens also organised a concert, again under the auspices of the Belgian Information Center, providing Belgian music for Belgian émigrés in New York, while at the same promoting American interest in Belgian music. On the programme was music from the 15th and 17th centuries by Guillaume Dufay, Jacob Obrecht and other Belgian composers. The concert was put on in cooperation with the Vassar Choir and held at the Hunter College Assembly Hall (Anonymous 1945).

Today, Charles Leirens' photographic work is mostly forgotten and has not been honoured in any exhibitions since the 1960s. It is also unknown where the photographer's estate is located. From 15 to 27 October, 1964, a retrospective on Charles Leirens was shown at the Palais des Beaux Arts in Brussels. In 1969 his portraits of Béla Bartók, Marc Chagall, André Gide and André Malraux were part of the Stretching the Medium exhibition at the Smithsonian Institute.