Ust-Bolsheretsky District (Russian: Усть-Большере́цкий райо́н) is an administrative and municipal district (raion) of Kamchatka Krai, Russia, one of the eleven in the krai. It is located in the southern and southwestern parts of the krai. The area of the district is 20,626 square kilometers (7,964 sq mi). Its administrative center is the rural locality (a selo) of Ust-Bolsheretsk. Population: 8,331 (2010 Russian census); 10,347 (2002 Census); 14,188 (1989 Soviet census). The population of Ust-Bolsheretsk accounts for 25.4% of the district's total population.