Sulejówek [sulɛˈjuvɛk] is a town in Poland, about 18 km east of Warsaw city centre and part of its metropolitan area. It is located in Masovian Voivodeship, in Mińsk County. Its population numbers 19323 (2011).
The town is well known in Poland as the place where Józef Piłsudski lived in the years between 1923 and 1926. The former manor houses a museum dedicated to him and is listed as a Historic Monument of Poland.
The oldest known mention of the settlement comes from 1526. Sulejówek was a private village of Polish nobility, administratively located in the Warsaw County in the Masovian Voivodeship in the Greater Poland Province of the Polish Crown.
In 1919, Polish composer and statesman Ignacy Jan Paderewski and his wife Helena Paderewska bought a villa ("Białynia") in Sulejówek and established an Educational Institute, which was financially supported by Marshal of Poland Józef Piłsudski. Piłsudski himself lived in another house ("Milusin") in Sulejówek in 1923–1926. It currently houses a museum dedicated to him, and is listed as a Historic Monument of Poland. Jędrzej Moraczewski, second Prime Minister of interwar Poland, also lived in Sulejówek, in the "Siedziba" Manor House.
During the German invasion of Poland which started World War II, on September 15, 1939, the Germans committed two massacres of Poles in Sulejówek and the present-day district of Długa Szlachecka, killing over 50 and 42 people respectively (see Nazi crimes against the Polish nation). Six Polish officers from Sulejówek were murdered by the Russians in the large Katyn massacre in April–May 1940.
The local football club is Victoria Sulejówek. It competes in the lower leagues.