Sierpiński was born in 1882 in Warsaw, Congress Poland, to a doctor father Konstanty and mother Ludwika (née Łapińska).

[3] In 1903, while still at the University of Warsaw, the Department of Mathematics and Physics offered a prize for the best essay from a student on Voronoy's contribution to number theory.

Sierpiński was awarded a gold medal for his essay, thus laying the foundation for his first major mathematical contribution.

To avoid the persecution that was common for Polish foreigners, Sierpiński spent the rest of the war years in Moscow working with Nikolai Luzin.

[7] During the Polish–Soviet War (1919–1921), Sierpiński helped break Soviet Russian ciphers for the Polish General Staff's cryptologic agency.

In 1920, Sierpiński, together with Zygmunt Janiszewski and his former student Stefan Mazurkiewicz, founded the mathematical journal Fundamenta Mathematicae.

[8] He retired in 1960 as professor at the University of Warsaw, but continued until 1967 to give a seminar on the Theory of Numbers at the Polish Academy of Sciences.

[10] Honorary Degrees: Lwów (1929), St. Marks of Lima (1930), Tartu (1932), Amsterdam (1932), Sofia (1939), Paris (1939), Bordeaux (1947), Prague (1948), Wrocław (1948), Lucknow (1949), and Moscow (1967).

For high involvement with the development of mathematics in Poland, Sierpiński was honored with election to the Polish Academy of Learning in 1921 and that same year was made dean of the faculty at the University of Warsaw.

In 2014, a sculpture in the form of a tree inspired by a fractal created by Sierpiński was unveiled at the Wallenberg Square in Stockholm as part of an exhibition organized by the Polish Ministry of Foreign Affairs on the 10th anniversary of Poland joining the European Union and 15th anniversary of Poland joining NATO.

[13] Another work of his published in English is the Elementary Theory of Numbers (translated by A. Hulanicki in 1964), based on his Polish Teoria Liczb (1914 and 1959).