He married at an early age the daughter of the wealthy Joel Heilpern, who provided for him and permitted him to occupy himself exclusively with his studies.

Adverse circumstances then forced him to accept a rabbinical position, and he became rabbi of Witkowo, from which place he was called later on to Lachovice.

Although a kabbalist, he disagreed with Rabbi Nathan Adler, who held separate services in his house according to the cabalistic ritual.

When Moses Mendelssohn's Biur on Pentateuch appeared, Horowitz denounced it in unmeasured terms, admonishing his hearers to shun the work as unclean, and approving the action of those persons who had publicly burned it in Vilna (1782).

Horowitz's chief work is "Hafla'ah," novellae on the tractate Ketubot, with an appendix, Kuntres Aharon, or Shevet Achim.