Janusz Jędrzejewicz 21 June 1885 – 16 March 1951) was a Polish politician and educator, a leader of the Sanacja political group, and Prime Minister of Poland from 1933 to 1934.

He joined Józef Piłsudski's Polish Socialist Party in 1904. After World War I broke out, he joined the Polish Legions and the Polish Military Organization. In 1918 he joined the Polish Army and served as aide to Piłsudski. In 1919 he was transferred to Section II (Intelligence) at the Lithuanian-Belarusian Front Headquarters, and later to the General Staff.

After the Polish–Soviet War, in 1923 Jędrzejewicz became a politician. He was elected a deputy to the Polish Sejm (1928–35) and later a senator. In 1930–1935 he was vice-president of the Nonpartisan Bloc for Cooperation with the Government (BBWR). From 12 August 1931, to 22 February 1934, he served as minister of education. He introduced a reform of Poland's educational system that came to be named, after him, "Jędrzejewicz reform." From 10 May 1933, to 13 May 1934, he was Prime Minister of Poland.

In 1926 he founded the monthly, Wiedza i Życie. In 1929 he organized a teachers' union, Zrąb, and other educational societies, including the Polish Academy of Literature. He was also co-author of the 1935 Polish Constitution. After Piłsudski's death in 1935, he opposed the Camp of National Unity (OZN, Ozon) and the right wing of the Sanacja movement, and retired from political life.

After the Soviet invasion during the Polish Defensive War of 1939, he fled to Romania and later through Palestine to London. In 1948 he was chosen to be head of Liga Niepodległości Polski, a political party in exile. He died in 1951.

He was a brother of Wacław Jędrzejewicz and married Cezaria Baudouin de Courtenay Ehrenkreutz Jędrzejewiczowa, a pioneer of ethnography in Poland.

Honours and awards

• Silver Cross of Virtuti Militari
• Cross of Independence with Swords
• Cross of Valour – twice
• Order of Polonia Restituta
• Order of the Cross of the Eagle, First Class (Estonia, 1938)