Mordechai Breuer (Hebrew: מרדכי ברויאר 1918–2007) was a German-Jewish historian and writer.
Breuer was born in Frankfurt am Main (Germany) to Isaac Breuer and his wife Jenny Breuer (née Eisenmann) in 1918. He had four siblings: Yaakov; Ulla, Tzipora, and Simeon. The family originated in Frankfurt but left for Israel in 1936.
Breuer wrote extensively on history, particularly German Jewish history. His works include Modernity Within Tradition: The Social History of Orthodox Jewry in Imperial Germany, (Columbia University Press: 1992) and The Torah-im-Derekh-Eretz of S.R. Hirsch (1970).