Sergiusz Piasecki was born on April 1, 1901 (or June 1, 1899) in Lyakhavichy, then in Northwestern Krai of the Russian Empire (now Brest Province, Belarus). The latter date was presented by Piasecki on several occasions, probably because he deliberately wanted to mislead the authorities. He was an illegitimate son of a russifed Polish nobleman Michal Piasecki and a Belarusian mother Klaudia Kukalowicz, a servant working for the Piasecki family, whom Sergiusz never met. According to his own life story, he was looked after by stepmother Filomena Gruszewska, a devout Catholic, who openly disliked him. His childhood was very difficult also, because children at school mocked his Polish roots, calling him "Lach" (which, in loose translation, is the Russian equivalent of the ethnic slur Polack). Conversely, Piasecki hated the Russian school – as he later explained – and in the seventh grade, armed with a pistol attacked the Teacher. Sentenced to jail, he escaped while in prison, and thus his formal education ended.

According to his autobiographical writing, at the time of the Bolshevik takeover of Russia in November 1917, Piasecki at age sixteen, found himself in Moscow. He saw with his own eyes the barbarity of the Bolshevik revolution, and from then on, became an avid anti-Communist. Some time in 1918 or 1919, he returned to Belarus, joining the Belarusian anti-Soviet units called Zialony Dub ("Green Oak"), led by ataman Wiaczeslaw Adamowicz. When in 1919 Polish Army troops captured Minsk in the Polish–Soviet War, Adamowicz decided to cooperate with them. Thus, a Belarusian unit under Polish command was created, and soon Piasecki was transferred to Warsaw's school of infantry cadets. In the summer of 1920, Piasecki fought in the Battle of Radzymin, and this experience tied him with Poland for the rest of his life. Afterwards, he was asked to join Polish intelligence, as his language skills (he spoke Russian and Belarusian fluently) were highly regarded.

In early 1920s, Piasecki skillfully organized whole web of Polish agents, covering the area of Soviet Belarus. His supervisors were very pleased with his work, but they did not have enough money to cover all expenses incurred by Piasecki and the growing number of his men. So, the enterprising agent found another source of income – smuggling. Moreover, this was not only about the money. Foreign spies as a rule were all executed by the Soviets, while smugglers were only incarcerated for a few years. As he wrote – he smuggled cocaine to the USSR, taking furs back to Poland. This provided him with a fortune, but Piasecki did not keep the money to himself. He needed it to bribe the Soviet prison guards, as his men were frequently caught and incarcerated. These events were later described by him in Kochanek Wielkiej Niedzwiedzicy.

In February 1926 Piasecki was fired from the Polish intelligence. It is not clear why this happened. Allegedly, he discovered connections between Soviets and some Polish V.I.P.'s. Also, he was at odds with his fellow smugglers. Destitute, he found himself in a desperate situation. All that he possessed was a revolver. In late July 1926, Piasecki was wandering in the forests south of Wilno. Armed, he decided to rob two Jews, Jodel Boryszanski and Morduch Drazlin, who were crossing the forest in a cart. He stole from them 1,054 zlotys, a gold watch and other items. Later, it was established that Piasecki was under the influence of cocaine, and he needed the money to cover bail for his friend, Antoni Niewiarowicz. A few days later, Piasecki and Niewiarowicz robbed a suburban train near Wilno, and, due to Niewiarowicz's lover's confession, they were caught, tried and put in jail in Lida.

Piasecki became a Writer by chance. Later, he confessed that many prisoners in Wronki would write, so he decided to emulate them. As his knowledge of standard Polish was poor, he would learn from a school book of Polish grammar. Some time in either 1935 or 1936, his prison prose came to the attention of a famous Novelist and Journalist, Melchior Wańkowicz, who toured Polish prisons as a reporter. After reading a manuscript of Kochanek Wielkiej Niedzwiedzicy, Wańkowicz encouraged Piasecki to continue his writing efforts and helped him to publish the book. The publication and resulting popularity of the book became the catalyst for getting Piasecki out of prison. The book was published while Piasecki was still in prison, and its copy was delivered to his cell. The book sold out within a month, it was the third most popular publication of interwar Poland.

Due to popularity of the book, Wańkowicz's efforts to release Piasecki were supported by other Writers and lawyers. Finally, in 1937 President Ignacy Mościcki pardoned him. The day of his release was sensational, crowds of journalists were waiting at a gate, and Piasecki himself was shocked at technical novelties, such as radio, which had become Common since 1926. In late 1937 and early 1938, Piasecki went to Otwock and Zakopane, to recuperate. Among others, he met Witkacy (Stanisław Ignacy Witkiewicz), who painted his portrait. Being a Celebrity, he avoided meeting with numerous readers, neither did he like signing of books.

Living abroad, Piasecki did not stop writing. In late 1940s he came to the conclusion that humor was the best weapon to fight the Communists. So, he wrote a satire The memoirs of a Red Army officer, which presents a made-up diary of Mishka Zubov - an officer of the Red Army, who, together with his unit enters Poland on September 17, 1939. Zubov claims in his "diary" that his only purpose is to kill all the bourgeoisie who possess watches and bicycles. Piasecki became fluent in Polish as an adult. Sergiusz Piasecki died in 1964 in London at the age of 65. On his tomb, located in Hastings Cemetery, England, it is said that he was born on June 1, 1899.

After the war, Piasecki hid from the secret police for a year inside Poland. In April 1946, he escaped to Italy, where he spotted the Italian translation of his own Kochanek Wielkiej Niedzwiedzicy. Soon, he got in touch with Polish Writers living in exile, including Jerzy Giedroyc. In 1947, Piasecki moved to England, his name can be found on a resolution of Union of Polish Writers in Exile, which urged all concerned to stop publishing in the Communist-occupied country. He once publicly declared that he would gladly take any job that would result in erasing Communism.

After the collapse of the Soviet empire, in early 1990s, Kochanek Wielkiej Niedźwiedzicy became again one of the best selling books in the country according to Rzeczpospolita daily. Another one of his novels, an anti-Soviet satire Zapiski oficera Armii Czerwonej (The memoirs of a Red Army officer), had already been reprinted several times.