Bojonegoro Regency (Indonesian: Kabupaten Bojonegoro, older spelling is Kabupaten Bodjanegara, Javanese: ꦑꦧꦸꦥꦠꦺꦤ꧀ꦨꦗꦤꦼꦒꦫ, romanized: Kabupatèn Bojånegårå) is a regency in East Java, Indonesia, about 110 km west of Surabaya. It is located in the inland part of northern Java plain, on the banks of the Solo River, the longest river in Java. It had a population of 1,209,973 at the 2010 Census and 1,301,635 at the 2020 Census, comprising 653,686 males and 647,949 females. The administrative centre of the regency is the town of Bojonegoro District.