Hacham Yitzhak Bar Sheshet Perfet was born in Barcelona, Spain, in 1336. He studied Torah with Hacham Hasdai Karashkesh the First, Hacham Peretz Ben Yitzhak Hacohen and with his principal teacher, Hacham Rabbeinu Nissim Ben Reuben Girondi, in Barcelona. As the result of anti-Semitic libels, he, and his teachers were arrested, as were additional community notables, and imprisoned for five months.
Hacham Yitzhak Bar Sheshet Berfet moved to Saragossa, where he officiated in the rabbinate for four years. It was there that his son, at the age of eight, died and there that he heard of his mother's and younger brother's deaths. He moved from Saragossa to Calatayud, and then to Valencia, where he served as a rabbi until the pogroms of 1391. That year, during an uprising of thousands of aristocrats and serfs against the Spanish monarchy, hundreds of Jews were murdered, many sold in slavery, and a great number forced to convert to Christianity. In Valencia alone, Hacham Yitzhak Bar Sheshet's city, 250 Jews were murdered. Many Jews left Spain for North Africa because of the pogroms, including Hacham Yitzhak Bar Sheshet and Hacham Shimon Ben Tzemach Duran, who both moved to Algiers. Hacham Yitzhak Bar Sheshet was greeted in Algiers as the community's leader and rabbinic judge. He was even accorded the appointment by the Muslim sovereign but refrained from accepting it out of deference for Hacham Shimon Ben Tzemach; in fact, he avoided taking on any official positions while Hacham Shimon Ben Tzemach was alive.
Hacham Yitzhak Bar Sheshet passed away on 2 Elul 5178 (1408). Because of the city's expansion, his and Hacham Shimon Ben Tzemach graves were relocated and are marked by a single tomb. A collection of 517 responsa is the only book that remains of his writings; his original commentary on part of the Talmud's tractates, some poetry, piyuttim and dirges were also preserved.