Sereni was born in Rome. His father was physician to the King of Italy. He grew up in a traditional Jewish Italian household but became a Zionist as a teenager and was one of the first Italian Zionists.
After obtaining his PhD in philosophy from the University of Rome, he emigrated to Mandate Palestine in 1927. He worked in orange groves in Rehovot and soon helped found kibbutz Givat Brenner. As an enthusiastic socialist, Sereni was also active in the Histadruttrade union. He was a pacifist who advocated co-existence with the Arabs and integration of Jewish and Arab society. Sereni was sent to Europe in 1931–1934 to help bring people to Palestine through the Youth Aliyah, and was arrested briefly by the Gestapo. He helped to organize the Hechalutz movement in Nazi Germany and was also involved in helping to smuggle money and people out of Germany. Sereni was also sent to the United States to help organize the Zionist movement there. During World War II, he joined the British Army, and was involved in disseminating anti-fascist propaganda in Egypt. The British sent him to Iraq, and Sereni spent part of his time organizing clandestine aliyah. In 1942, Sereni became one of the first Jewish emissaries from Palestine to Iraq and visited Sandur, a Jewish village in northern Iraq and described it in detail. The village was located an hour and a half's drive from Mosul, in a valley between two walls of rock. It was completely green and "full of gardens of fruit, pears, grapes, plums, pomegranates, apples." Sereni got in trouble with his British superior officers for his Zionist views and was imprisoned briefly for forging passports. Sereni then helped organize the Jewish parachute unit of the British Special Operations Executive that sent agents into occupied Europe. Of about 250 volunteer trainees, about 110 were selected for training, and 33 were actually parachuted into Europe, including Sereni, despite his relatively advanced age. On 15 May 1944 he was parachuted into Northern Italy but was captured immediately. According to records, he was shot in Dachau concentration camp on 18 November 1944. Other famous martyrs who parachuted into Europe with this unit include Hannah Szenes and Haviva Reik. Kibbutz Netzer Sereni is named after him, as are many streets throughout Israel. Sereni wrote several books and numerous articles.
