Siegfried Bernfeld was born in Lemberg, Galicia, (now Lviv in the Ukraine). He studied physiology, pedagogy and psychology at the University of Vienna and the University of Freiburg, Germany. In 1913-1914 he published Der Anfang, a youth magazine in Berlin. In World War I Bernfeld served in the Austro-Hungarian Army. After his release from service until 1920 he was a pedagogic reformer, promoting progressive education, influenced by the German educator and philosopher, Gustav Wyneken. Concurrently, in 1917–1918 Bernfeld was active in a Jewish youth movement. The youth rally, which he initiated in Vienna, in May 1918, resulted in founding the Verband der juedische Jugend Oesterreich, of which Bernfeld became president. From 1918 to 1919 he was editor of Jerubbaal, a monthly Jewish youth journal. In 1918 he was also appointed Secretary of the Jewish National Council. In the same year he was co-founder of the Hebrew Pedagogium, Vienna, for training teachers in Jewish subjects, founded by the Joint(American Jewish Joint Distribution Committee). In 1919-1920 Bernfeld was co-founder and director of Kinderheim Baumgarten for Jewish orphans from Eastern Europe, also founded by the Joint. In 1920 Bernfeld became private secretary to Martin Buber. Concurrently he was assistant editor of Der Jude. Bernfeld was the founder of the Jewish Institute for Research into Adolescence and Education. His other works of Jewish interest include Das juedische Folk und seine Jugend (1920).
Bernfeld was a student of Sigmund Freud and from 1920 to 1926 he had a private clinic of psychoanalysis in Vienna. He taught psychoanalysis in Vienna and Berlin, and later also in Menton, France. In 1924 he became secretary of the Viennese Psychoanalytical Society, and vice-director of the Vienna Psychoanalytical Institute.
In 1926 Bernfeld moved to Berlin, where he became a member and training analyst at the Berlin Psychoanalytical Institute.
In 1932 he returned to Vienna. He gave courses during the winter semester of 1932/33, which had the highest attendance figures of all the courses at the Institute. Bernfeld also had close ties to the Vienna Circle philosophers and other humanities.
In 1934 Bernfeld immigrated to France, where he was engaged in private practice and research. In 1936 he moved on to the USA and settled in San Francisco, where he held a private practice until 1952. Concurrently he was a member and training analyst at the San Francisco Psychoanalytical Institute. In 1952 he resigned from his post and became lecturer at the Medical School of the University of California. Bernfeld was also a staff member of Mount Zion Hospital, San Francisco. In collaboration with wife he conducted researches and published important papers on the early creative years of Sigmund Freud, incorporated into Ernest Jonh’s biography of Freud.