In 1913 he graduated from the gymnasium in Jaslo and enrolled at the Faculty of Law of the Jagiellonian University.
In 1914 he joined the Eastern Legion, and at its dissolution he was drafted into the Austrian army. After graduating from the school of infantry officers he was sent to the Italian front as a platoon leader. In 1915 he was appointed a standard-bearer, in 1916 - a second lieutenant.
By the end of World War I he had been wounded three times and served as a company commander.
From November 1918 served in the Polish Army. Between November 1918 and October 1925 he was a company and battalion commander in the 16th Infantry Regiment, Tarnów and during the war with the Bolsheviks, he commanded the regiment (31VII-4VII11920).
During the years 1930–1934 he was professor of tactics at the Higher Military School in Warsaw. Between January 1934 - 1936 - Deputy Commander of the 18 Infantry Regiment in Skierniewice.
1936 - 1938 - Commander of the 5th Podhale Rifles Regiment in Przemyśl.
From 1938 to September 1939 he was Head of the course at the Higher Military School in Warsaw, after which he was appointed to the Division III of the General Staff as a Chief of the Department of Operations. After the September campaign he moved to France. December 1939 – June 1940 Head of Division III, Polish General Staff in France.
July 1940 – July 1943 Chief of the General Staff of the Supreme Commander in London.
He died in the plane crash on July 4, 1943, in Gibraltar, together with the Polish Prime-Minister and Commander-in-Chief General Władysław Sikorski and his staff Tadeusz Klimecki was buried in the cemetery of Polish airmen in Newark-on-Trent, England.
On December 3, 2010, bodies of Tadeusz Klimecki, Andrzej Marecki and Jozef Ponikiewski were exhumed, flown to Warsaw and then taken to the Department of Forensic Medicine in Cracow for examination. On December 9, 2010 Tadeusz Klimecki and Andrzej Marecki were buried in the Powązki Military Cemetery in Warsaw.
Captain - since June 1, 1919
Major - since July 1, 1925
Lieutenant Colonel - since January 1, 1931
Colonel - since March 19, 1938
Brigadier - since February 6, 1941
Commander"s Cross with Star of the Order of Polonia Restituta
Cross of Valour.