Andrzej Klimowicz was born in Biała Cerkiew in Ukraine. As a student of Władysław Giżyński Gymnasium in Warsaw, he was engaged in the activity of the Association of Independent Socialist Youth “Spartakus”. Later, when he was a student of the School of Political Science, he cooperated with the Organization of Socialist Youth “Życie”. In 1938, he joined the Democratic Club in Warsaw and, as early as in 1939, he became a member of its Management Board. He was also one of the founders of a youth monthly Mosty and, as its publicist, was invited by the Zionist youth organization Gordonia to their hachshara (the camp preparing youth for work in Palestine under the British mandate) in Zduńska Wola, where he spent a month. He took part in the September Campaign in the Workers' Battalions for Warsaw Defence.
During the German occupation, he engaged in the underground activity of the Democratic Party, the pseudonym “Prostokąt”, he also became a representative of the Youth Section in the Management Board of that party. After the split in the Democratic Party, he moved to the Polish Democratic Party and was a member of its Management Board. In 1944, he became a member of the Youth Section of the State National Council.
The vulcanization workshop which he managed at 41 Nowy Świat Street was a place of meetings of underground activists – of the Social Self-Defence Organization led by Zofia Kossak (“Weronika”) and the “Żegota” Council to Aid Jews – Adolf Berman (“Borowski”), Salo Fiszgrund (“Henryk”) and Leon Feiner (“Mikołaj”). Through Klimowicz, the Jews hiding in Warsaw received false documents, addresses of hiding places as well as financial support. The workshop was also a hiding place for Jankiel Wiernik (1889–1972) who escaped from Treblinka on 2nd August 1943 and came to Warsaw. Behind the partition wall in Klimowicz's workshop, he wrote the testimony entitled Rok w Treblince (A Year in Treblinka). Klimowicz did not know the majority of those whom he had helped, he did not remember their names after the war. One of the exceptions was Menachem Benesis, a doctor from Lwów.
Read the story of Marian Wnuk, who contributed to the establishment of the “Żegota” printing-house in the same place – at 41 Nowy Świat Street in Warsaw.
In the Warsaw Uprising, Klimowicz fought in the Security Corpse, then he swam across the Vistula River and joined the Polish Army. He was a cooperative activist, a member of the Krajowa Rada Narodowa (State National Council, 1945–1946) and the Związek Bojowników o Wolność i Demokrację (League of Fighters for Freedom and Democracy). He was awarded the Knight's Cross of the Order of Polonia Restituta, the Virtuti Military Cross 5th class, the Cross of Valor and the the Partizan Cross. After the war, he reopened the rubber goods workshop. He established a family and lived to see two daughters and grandchildren.
In 1979, in her testimony on Klimowicz for the Jewish Historical Institute, Irena Sendlerowa underlined that “all the time during the war, in his gratuitous and humanitarian activity involving the saving of the persecuted from death, constantly endangered his own life and his closest ones”.
In 1981, Yad Vashem granted Andrzej Klimowicz the title of the Righteous Among the Nations. In 1982, in connection with the ceremony of awarding the title, he visited Israel and met in Ma’ale Hahamisza kibbutz with the people who he remembered from Zduńska Wola. He was one of the initiators of founding the Polish Association of the Righteous Among the Nations.