The Rajah rat is a nocturnal forest-floor rodent. Its coat includes stiff spines, and its tail is dark above and paler below.
The upperparts are dull brown and may be tinged with red or orange. The underparts are white, sometimes with a dark midline streak in adults, and stiff hairs are mixed into the back fur.
It is active at night on the ground in mature forest and eats fallen fruit, shoots, and insects.
An extinction-risk assessment has not been added yet.