Mirninsky District (Russian: Ми́рнинский район; Yakut: Мирнэй улууһа, Mirney uluuha) is an administrative and municipal district (raion, or ulus), one of the thirty-four in the Sakha Republic, Russia. It is located in the west of the republic and borders Olenyoksky District in the north and northeast, Nyurbinsky and Suntarsky Districts in the east, Lensky District in the south, and Irkutsk Oblast and Krasnoyarsk Krai in the west. The area of the district is 165,800 square kilometers (64,000 sq mi). Its administrative center is the town of Mirny. As of the 2010 Census, the total population of the district (excluding its administrative center) was 38,802.