Bonawentura Niemojowski (Polish pronunciation: [bɔnavɛnˈtura ɲɛmɔˈjɔfskʲi]; 4 September 1787 - 15 June 1835) was a Polish lawyer, writer and politician. He was one of the leaders of Polish National Government during the November Uprising.
Bonawentura Niemojowski was born in Słupia near Kępno to a noble (szlachta) family (Wierusz Coat of Arms). He first studied in the Piarist college in Warsaw, and later abroad in Paris. After returning to Poland, he became elected from the Kalisz Voivodeship to the Sejm (parliament) of Congress Poland. He was a member of the liberal Kalisz Opposition (Kaliszanie) in the parliament since 1820; the group was named after the voivodeship which he and his brother, Wincenty Niemojowski, both notable members of the group, were from.
In 1821 married Bonawentura Wiktoria Lubowidzka, with whom he had two children.
In the Sejm, Bonawentura soon became a major nuisance to the Russian officials. One of the demands of the Kalisz faction in 1820, regarding independence of the judiciary, led the tsar Alexander I of Russia (who was also king of Congress Poland, the Russian Empire puppet state) to suspend the Polish parliament for a period of five years; Niemojowski was dismissed from the parliament before that and subject to house arrest for over a year. After the parliament was reestablished, he was a vocal opponent to the movement to make the parliament debates secret, and criticized the tsar's and Russian officials breaking the Constitution of the Congress Poland. In 1830 tsar ordered the Senate of Poland to annul Niemojowski's and his brother's mandates on a technicality in order to bar them from attending the parliament sessions.