Atmospheric sludge metal is a Post-Metal subgenre that takes the dense, punishing textures of Sludge Metal with an extensive, otherworldly atmosphere, performed with an emphasis on atmospheric and textured riffs. It mainly draws inspiration from progressive stylings in order to accentuate on instrumental prowess and long-form compositions to create immersive and evolving soundscapes.

The genre was pioneered by bands driven by a desire to explore more atmospheric and expansive sonic territories within the Metal framework, such as Neurosis, Isis and Pelican. Atmosludge bands often had roots in Hardcore Punk, but mainly in Post-Hardcore, maintaining a mix of aggressive and melodic elements with complex song structures, and a willingness to experiment with different musical styles. These bands and others (Cult of Luna, Rosetta) also draw elements from Post-Rock, which is also a main feature of post-metal.