Vilyuysk is a town and the administrative center of Vilyuysky District in the Sakha Republic, Russia, located on the Vilyuy River, about 600 kilometers (370 mi) from Yakutsk, the capital of the republic. As of the 2010 Census, its population was 10,234.

Vilyuysky District is an administrative and municipal district, one of the thirty-four in the Sakha Republic, Russia. It is located in the western central part of the republic and borders with Zhigansky District in the northeast, Kobyaysky District in the east, Gorny District in the south, Verkhnevilyuysky District in the west, and with Olenyoksky District in the northwest. The area of the district is 55,200 square kilometers (21,300 sq mi). Its administrative center is the town of Vilyuysk. Population: 25,222 (2010 Russian census); 25,696 ; 28,704 (1989 Soviet census). The population of Vilyuysk accounts for 40.6% of the district's total population.