The study of the gut microbiota by the “culturomics concept” permitted us to isolate, from human stool sample, an unknown anaerobic bacterium within the genus Clostridium for which we propose the name Clostridium massiliamazoniense sp. nov. It was isolated from the fecal flora of a healthy 49-year-old Brazilian male. Here, we describe the characteristics of this organism and its complete genome sequencing and annotation. Clostridium massiliamazoniense sp. nov., ND2T (= CSURP1360 = DSMZ 27309) is a Gram-positive, obligate anaerobic member of Firmicutes with a 3,732,600 bp-long genome and a G+C content of 27.6%.