Gabriël Kousbroek was born in Neuilly-sur-Seine, France. He attended the Rietveld Art Academy in Amsterdam between 1986 and 1990. He started contributing to fanzines and schoolpapers in the 1980s and has since published his work in magazines like De Groene Amsterdammer, De God van Nederland and De Volkskrant.
His parents were the Dutch writers and essayists Rudy Kousbroek and Ethel Portnoy, and his sister was translator and writer Hepzibah Kousbroek. Since both his parents and his sister have passed away, Gabriël, or Gaab, is the last of the illustrious Koubroek dynasty. He chronicled his life and his experiences with his parents and their befriended writers in his honest and sometimes merciless autobiography 'Kousboek', that was published by Nijgh & Van Ditmar in 2013. This partially written and partially comic story, was first published in installments in De God van Nederland. Since 2015, he irregularly self-publishes the satirical comics magazine Anus.