Sepia cottoni is a species of cuttlefish native to the southeastern Indian Ocean, specifically from northwest of Broome (17°31' S) to Armstrong Point, Rottnest Island (32°0' S). It lives at a depth of between 83 and 183 m.S. cottoni grows to a mantle length of 55 mm.The type specimen was collected west of Lancelin, Australia (31°54′S 114°55′E). It is deposited at the Western Australian Museum in Perth.