The Shark Bay mouse is found on Bernier Island in Shark Bay. There are also said to be translocated populations on Doole Island of the Exmouth Gulf and North West Island of the Montebello Islands. It is a robust mouse with a long and shaggy coat that is yellowish-gray in color with lighter underparts. Its tail is gray on the top and white underneath. Adults reach up to 115 mm in head and body length, and their tails grow up to 125 mm. They can weigh between 30 and 61 grams.
The Shark Bay mouse prefers sand dunes located at cliff bases and coastal sandy areas for its habitat. Shark Bay mice found on North West Island have been seen using scree slopes for shelter. The Shark Bay mouse is known to dig tunnels and runways in heaps of seagrass piled up on beaches during storms and in the day they use ground nests as refuges. Diet consists of green vegetation and flowers, fungi, insects, and spiders. Breeding can occur year round, and the females give birth to three to four young mice after a gestation period of 28 days. In captivity, the males help to care for the young, but it is not known if they do so in the wild. The young remain dependent of the mother for 30 days after birth. The lifespan of the Shark Bay mouse is only about two years.
Threats to the species are not fully known. Loss of their food source due to grazing and competition with other species and predation by introduced species such as cats may be contributing factors.