Kotlassky District is an administrative district (raion), one of the twenty-one in Arkhangelsk Oblast, Russia. As a municipal division, it is incorporated as Kotlassky Municipal District. It is located in the southeast of the oblast and borders with Krasnoborsky District in the north, Lensky District in the northeast, Vilegodsky District in the east, Luzsky District of Kirov Oblast and Velikoustyugsky District of Vologda Oblast in the south, and with Ustyansky District in the west. The area of the district is . Its administrative center is the town of Kotlas (which is not administratively a part of the district). Population:

The district is located on both banks of the Northern Dvina River and its main right tributary, the Vychegda. The Northern Dvina and the Vychegda divide the district into three comparably sized areas.