Hacham Yitzhak Buchnik was born to (mother) Bahria in 1915 in Gabès, Tunisia.
He studied Torah with Hacham Matzliakh Mazouz and is considered his outstanding student; he also studied with Hacham David Kartoza and Hacham Yeshua Elimelech. Hacham Yitzhak Buchnik was proficient in Torah and in the sciences, and was fluent in French and Arabic. He served as Rosh Metivta in the Hevrat HaTalmud yeshiva, and gave Torah classes in synagogue; he taught during vacation periods as well.
Hacham Yitzhak Buchnik married Camissa, daughter of Hacham Yeshua Elimelech. Their son, Hai Menachem, died in a car accident in Toulouse, France in 1963. In 1975, Hacham Yitzhak Buchnik was flown to Israel for emergency medical treatment.
Hacham Yitzhak Buchnik passed away on 26 Shevat, 5735 (1975) and was buried on the Mount of Olives. His writings were published in a book entitled Vayomer Yitzhak, which contains original commentary on the Talmud, sermons and Responsa, as well as some of his son Hai Menachem's sermons.