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.

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.