He was born on 20 May 1919 in Kielce into the family of Dorota, née Bryczkowska, and Jakub Herling aka Grudziński. From 1929, he studied at the Mikołaj Rej Boys’ High School in Kielce where he passed his maturity examination in 1937. After that, he studied Polish philology at the Józef Piłsudski University in Warsaw. During his studies, he was editor of the literary section of a magazine entitled Hard Graft [Polish: Orka na Ugorze], an author writing for the literary section of the biweekly magazine Transformations [Polish: Przemiany], and he also published his texts in such titles as Our Word [Polish: Nasz Wyraz], Athenaeum [Polish: Ateneum], Perpendicular [Polish: Pion],  and Pen [Polish: Pióro]. During the two years of his studies, he published about thirty texts.

He did not take part in the September Campaign, but as early as 15 October 1939, along with his friends, he founded the Polish People’s Independence Action [Polish: Polska Ludowa Akcja Niepodległościowa] where he held the post of Chief of Staff. Together with his colleagues, he edited and published two issues of the underground Polish Bulletin [Polish: Biuletyn Polski]. In November, he left for the West through Lithuania as an emissary to inform the western states about the events which occurred in Poland after the German invasion. In 1940, he was arrested by the NKVD, accused of espionage and sentenced to five years in a forced labour camp.

He was imprisoned in the camp in Yertsevo near Arkhangelsk on the White Sea coast where he worked as a carrier in a food base and worked in fields. After the Sikorski-Mayski Agreement was signed, he waited in vain for his release. Ravaged by disease, undernourishment and overwork, he decided to go on hunger strike. On 20 January 1942, he was allowed to leave the camp, and on 12 March he reached Lugovoye where he joined the Polish Army of General Władysław Anders which was being formied in the territory of the Soviet Union. He was assigned to the 3rd Carpathian Light Artillery Regiment. In 1942, he went with the Regiment to the Middle and Near East.

He described his experiences from the labour camp in a book entitled A World Apart [Polish: Inny świat] which is one of the most important testimonies in the literature on the subject of Gulags. In 1943, he started to cooperate with and befriended Józef Czapski and Jerzy Giedroyc. He returned to writing, and in 1943 his articles appeared in such magazines as Polish Courier in Baghdad [Polish: Kurier Polski w Bagdadzie), Journal of a Soldier of Polish Armed Forces in the East [Polish: Dziennik Żołnierza APW], On the Way [Polish: W Drodze] and White Eagle [Polish: Orzeł Biały]. As a soldier of the 3rd Carpathian Rifle Division of the 2nd Polish Corps, he took part in the Battle of Monte Cassino as a radio operator. He declined an offer to join the Press and Propaganda Department and continued to fight in the Italian campaign as a simple bombardier. After the end of the Italian campaign, he took up the post of literary editor at the editorial office of White Eagle [Polish: Orzeł Biały] in Rome. He was awarded the Virtuti Militari Cross for his valour. He then attended a course at the Artillery Reserve Cadet School in Matera, which he completed on 15 February 1945.

After the end of hostilities, he decided not to return to communist-ruled Poland, and chose political exile. He worked as a feature writer, and from 1946 was an active member of the Polish Socialist Party. In the years 1952-1955, he worked for Radio Free Europe, and then devoted himself to writing. He maintained contact with the Polish opposition, he was one of the foreign signatories of the protest against the amendments to the Constitution of the Polish People’s Republic, he cooperated with the Workers’ Defence Committee [Polish: Komitet Obrony Robotników] and the Polish Independence Alliance [Polish: Polskie Porozumienie Niepodległościowe].

In 1990, he was awarded the Order of the White Eagle. He died on 4 July 2000 in Naples and was buried in the Poggio Reale cemetery there. In commemoration of this outstanding figure, 2019 was designated the Year of Gustaw Herling-Grudziński.