He was born in Lviv and started already as a young man to write in Yiddish, studied later at German universities and at the Hochschule für die Wissenschaft des Judentums in Berlin. Since 1884 he worked for the Ha-Maggid and Ha-Meliz. From 1896 to 1900 he was a rabbi in Đakovo, Croatia. Still before Herzl, Ehrenpreis, Birnbaum and others were engaged to define the concept of a new national Judaism. Mordecai Ehrenpreis was an early adherent to Zionism and helped Herzl to establish the first Zionist Congress. He was a member of the Democratic Faction of the World Zionist Organization and on the editorial board of the Jüdische Almanach.
From 1900 to 1914 he was in Sofia as Chief rabbi of Bulgaria and also publisher of several Spaniolic magazines. After 1908 his interest in zionism and in the Hebrew literature decreased noticeably which earned him some criticism; he devoted himself to other literary works and to his tasks as a Rabbi. From 1914 up to his death he was Chief rabbi of Stockholm.
In 1928 he founded the Judisk Tidskrift, was engaged as a translator as well as scientific writer for different encyclopedias, since 1935 he became a professor at Stockholm University. During his time in Sweden he published some 20 books in Swedish.
Ehrenpreis, in his texts, emphasized the importance of seeking understanding for Jewish culture in the modern world and sought to create a synthesis between a general culture and the inherited culture of the Jewish minority.
In 1977 ultra-Orthodox (haredi) activist Moshe Schonfeld in "The Holocaust Victims Accuse" (published by Neturei Karta, an openly anti-Zionist group) claimed that the Swedish government wished to admit 10,000 German Jewish refugees during the Nazi era, and that Ehrenpreis asked the government to desist from this action. However, there never was such a plan by the Swedish government.
Ehrenpreis was the chairman of another committee, Arbetsutskottet för hjälp åt Polens judar, devoted to sending aid in the form of food, medicine, clothes and money, primarily to Poland but increasingly also to other parts of Nazi-occupied Europe.
Ehrenpreis was also the Chairman of the Swedish Section of World Jewish Congress from its institution in 1944 and was succeeded by historian and pioneering scholar of antisemitism, Hugo Valentin. Ehrenpreis was also involved in planning the attempt by Raoul Wallenberg to rescue Hungarian Jews. Wallenberg visited him at his home on 5 July, the evening before he left for Budapest. Ehrenpreis was consequently one of the last people to see Wallenberg alive in Sweden.
- Ognjen Kraus (1998, p. 173)
- Lexikon des Judentums, Gütersloh 1971
- Theodor Herzl, Briefe und Tagebücher, Berlin/Frankfurt a. M./Wien 1983-1996
- Svante Hansson, Flykt och överlevnad..., Stockholm: Hillel, 2004, pp. 75-76, 121, 266.
- Stephen Fruitman, Creating a New Heart : Marcus Ehrenpreis on Jewry and Judaism, Umeå 2001.
- Rudberg, Pontus, "‘A Record of Infamy’: the use and abuse of the image of the Swedish Jewish response to the Holocaust", Scandinavian Journal of History, Volume 36, Issue 5, Special Issue: The Histories and Memories of the Holocaust in Scandinavia (2011).
- Rudberg, Pontus, "The Swedish Jews and the victims of Nazi terror, 1933-1945", Studia Historica Upsaliensia 253 (2015)
- The personal papers of Mordecai Ehrenpreis are kept at the Central Zionist Archives in Jerusalem