During pre-war period he was a Vice President of Warsaw (1935-1939) under Stefan Starzyński, with whom he actively led a defense of city during Invasion of Poland. He was named by German occupation authorities the President after Starzyński was arrested. Kulski accepted this post with advice of resistance movement and Polish Government in Exile and during his tenure actively working with them against occupation forces, always remained loyal to Poland.
Before he became a part of Warsaw municipal government he served in the Polish Legions in World War I (1914-1917), and Polish Army (1919-1921). He was also a commander of the People's Militia in Warsaw (1918-1919) and longtime high-rank employee of the Ministry of Treasury.
Because of his accomplishment during the war, Kulski remained widely recognized.
Julian's son, also called Julian Kulski (3 March 1929 - ) was a member of the Polish Underground during the war from ages 12 to 15. He published a book and a video about his experiences called "Legacy of the White Eagle" in 2006. He moved to the US and became a prominent architect.