In 1990 the high school expanded to include a girls' division, known as Machon Sarah.

Graduates from Ottawa Torah Institute earn an Ontario Secondary School Diploma.

In 1981, Reuven Bulka brought a Jewish educational program from Yeshivas Chofetz Chaim to Machzikei Hadas synagogue.

In 1982, this was followed by Rabbis Yisroel Morgenstern and Yaakov Deitsch of Yeshivas Chofetz Chaim opening a Yeshiva High School for boys and establishing OTI as Ottawa's first full-time Jewish high school for boys.

Rabbi Eliezer Ben-Porat was head of school for twenty five years.