Glass was born in Petah Tikva, in the British Mandate of Palestine, in 1937. During the Second World War, his father worked for the British Army, and for a while the family moved to Haifa. He learned to play the violin. His brother Hilik was born when he was thirteen. He was drafted to the Israel Defense Forces and was sent to a basic training camp for physically unfit soldiers. He then served in the Israeli Intelligence Corps. He changed his last name to Kenaz, after Othniel Ben Kenaz, a bibilical name with a similar sound.
He studied Philosophy and Romance languages at the Hebrew University, and French literature at the Sorbonne. He wrote his first story in Paris and sent it to Aharon Amir's Keshet journal under the name of Avi Otniel (literally "father of Othniel"). He became famous in Israel in 1986 when his novel Infiltration became a best seller.
He has translated many French classics into Hebrew, and has worked on the editorial staff of the Ha'aretz newspaper. He was awarded the Alterman Prize in 1991, the Newman Prize in 1992, the Agnon Prize (1993), the Acum Prize (1994) and the Bialik Prize (1995). In 2007, Infiltration was named one of the ten most important books in Israeli history. As of August 2008, a film adaptation of his book On the Way to the Cats is in post-production, directed by Jorge Gurvich, while Infiltration is still in pre-production. He lives in Tel Aviv.
Kenaz has said he is not a Zionist because he does not believe a Jewish state would solve the problem of antisemitism. He supports a two-state solution to the Israeli-Palestinian conflict because he wants the Hebrew language and culture to be hegemonic and more cultivated in Israel.
After the Holidays (1964) is about the disintegration of a family in a small farming community in Palestine during the British Mandate. The Great Woman of the Dreams (1973) depicts the lives of the tenants of a rundown apartment house in Tel Aviv. Musical Moments (1980) is a collection of four stories dealing with themes of the rites of manhood and the disruption of innocence. Infiltration (1986) is the story of a platoon of young recruits with minor physical disabilities during their basic training at an Israeli army camp in the 1950s. The Way to the Cats (1991) tells the story of pensioners in an old-age home, who engage in a pathetic power struggle. Returning Lost Loves (1997) runs several plots in parallel form, sharing common characters. Landscape With Three Trees (2000) is two stories about the changes undergone by the Israeli society from the pre-state days to the present-day era.
