Bulunsky District (; , Buluà  uluuha) is an administrative and municipal district (raion, or ulus), one of the thirty-four in the Sakha Republic, Russia. It is the most northerly district of the republic, and includes the offshore New Siberian Islands. Bulunsky borders Ust-Yansky District in the east, Verkhoyansky District in the southeast, Eveno-Bytantaysky and Zhigansky Districts in the south, Olenyoksky District in the west, and Anabarsky District in the northwest. The area of the district is . Its administrative center is the urban-type settlement of Tiksi. As of the 2010 Census, the total population of the district was 9,054, with the population of Tiksi accounting for 55.9% of that number.
The district is washed by the Laptev Sea in the north. The main river in the district is the Lena, with its tributaries Eyekit, Molodo and Syungyude. Other rivers include the Olenyok, with the Khorbusuonka and the Kyuyutingde, as well as the Omoloy and the Khara-Ulakh. There are many lakes in the Lena River delta. The Lena Delta Wildlife Reserve is located in the district.
Average January temperature varies from on the coast to in the interior and average July temperature varies from in the north to in the south. Average precipitation ranges from in the north and from in the south.
The district was established on December 10, 1930. Initially, its administrative center was in the selo of Kyusyur. In 1957, the administrative center was moved to Tiksi.
Within the framework of administrative divisions, Bulunsky District is one of the thirty-four in the republic. It is divided into one settlement (an administrative division with the administrative center in the urban-type settlement (inhabited locality) of Tiksi) and eight rural okrugs (naslegs), all of which comprise nine rural localities. As a municipal division, the district is incorporated as Bulunsky Municipal District. The Settlement of Tiksi is incorporated into an urban settlement, and the eight rural okrugs are incorporated into six rural settlements within the municipal district. The urban-type settlement of Tiksi serves as the administrative center of both the administrative and municipal district.
The economy of the district is mostly based on reindeer husbandry and fishing. Tiksi is a sea port on the Northern Sea Route.
As of the 2021 Census, the ethnic composition was as follows: