He was the youngest of nine kids of Jan Dekutowski, patriotic member of Polish Socialist Party and follower of Józef Piłsudski.

His mother Maria Zofia Dekutowska (née Sudacka), did not work and stayed at home, taking care of the kids.

At the same time, he was a member of local branch of Związek Harcerstwa Polskiego, where he was a leader of a group of teenagers, as well as Catholic organization Sodality of the Blessed Virgin.

After graduation and failing final exams (May 1938), Dekutowski worked for Count Artur Tarnowski, one of the biggest landowners in the 1930s Poland.

After a few more months, in the night of 16/17 September 1943, during "Operation Neon 1", he was dropped on a parachute, together with other Cichociemni - Bronisław Rachwał and Kazimierz Smolak.

He ordered six smaller Kedyw units to join forces, thus creating a strong, mobile regiment, capable of shock attacks on German outposts and troops.

A communist commandant of precinct of Urząd Bezpieczeństwa in Chodel named Abram Tauber, who had been saved by Dekutowski and his men during the war, invited four members of the Home Army to his headquarters.

In the spring of 1945 he organized several bold attacks on Communists, among them: In June, Dekutowski, promoted to major, retreated towards the Janowska Wilderness and put away weapons, telling soldiers to give up fighting and return to homes.

In early 1947, when the government declared amnesty, he planned to give up fighting, but found out that several of his men had been arrested and continued hiding in the woods until mid-1947.

According to witnesses, even though he was 30 at the moment of death, he looked like an elderly man, without teeth and nails, with grey hair, broken ribs, nose and hands.

Hieronim Dekutowski, and his six soldiers remains were found in the summer of 2012, at the headquarters " Ł " at the Powązki Military Cemetery in Warsaw.