Itzhak Katzenelson was born to a Jewish family in Karelichy, Belorussia (present-day Korelichi, Belarus). His father Jakob Benjamin Katzenelson was a teacher and writer. Soon after Itzhak's birth, the family moved to Łódź, Poland, where he grew up. He began writing at an early age and was considered a child prodigy. By age 12, he had already had written his first play, Dreyfus un Esterhazy, which he performed with other young people at his home. Together with members of his family, he founded a Hebrew kindergarten, grade school, and secondary school. He became a teacher, writing the textbooks and children's books in Hebrew. His first collection of poetry, Dimdumim (Twilight), was published in two volumes in 1910. He also helped found Ha-Bamah ha-Ivrit (The Hebrew Stage) Theater Company, which performed his plays as well as works by Sholem Aleichem and others, and took it on tours of Poland and Lithuania prior to World War I. After Nazi Germany invaded Poland in 1939 in World War II, Katzenelson, his wife Hanna and their three sons fled to Warsaw, where they were confined in the Ghetto. There he ran the clandestine school and published poems, short plays and articles in the underground Zionist newspaper Dror (Freedom). His wife and two younger sons were deported to the Treblinka extermination camp and murdered there.
Katzenelson and his older son Zvi participated in the Warsaw Ghetto Uprising in 1943, and afterwards were deported to a detention camp in Vittel, France. There Katzenelson wrote a diary and his most famous work, the epic poem Dos lid funem oysgehargetn yidishn folk (Song of the Murdered Jewish People), which he put into bottles and buried under a tree. Another copy was sewn into the handle of a suitcase.
From Vittel, the Katzenelsons were sent to the death camp at Auschwitz, where they were killed. The manuscripts were retrieved from their burial spot after the war by survivor Miriam Novitch. The other copies in the suitcase handle were saved by Ruth Adler, a German Jew with a British Mandate of Palestine passport, who smuggled them out and took them to Israel. Vittel Diary: 22.5.43 – 16.9.43 and Song of the Murdered Jewish People were both published and translated into several different languages.