Selenginsky District (; ) is an administrative and municipal district (raion), one of the twenty-one in the Republic of Buryatia, Russia. It is located in the center of the republic. The area of the district is . Its administrative center is the town of Gusinoozyorsk. As of the 2010 Census, the total population of the district was 46,427, with the population of Gusinoozyorsk accounting for 52.9% of that number.