Ust-Koksinsky District (Russian: Усть-Ко́ксинский район; Altay: Кӧк-Суу аймак) is an administrative and municipal district (raion), one of the ten in the Altai Republic, Russia. It is located in the west and southwest of the republic. The area of the district is 12,960 square kilometers (5,000 sq mi). Its administrative center is the rural locality (a selo) of Ust-Koksa. As of the 2010 Census, the total population of the district was 17,020, with the population of Ust-Koksa accounting for 25.7% of that number.