Osinsky District (; , Ohyn aimag) is an administrative district of Ust-Orda Buryat Okrug of Irkutsk Oblast, Russia, one of the thirty-three in the oblast. Municipally, it is incorporated as Osinsky Municipal District. It is located in the south of the oblast. The area of the district is . Its administrative center is the rural locality (a selo) of Osa. Population: 20,962 (2002 Census); The population of Osa accounts for 22.1% of the district's total population.