The New Guinean Planigale occurs only on New Guinea. In the south of the island, it is reported from coastal plains south of the highlands, where it is restricted to savanna and grassland.
A 2026 study of planigales reports that some large male New Guinean Planigale specimens have tails reaching about 80 mm.
Savanna and grassland are listed as habitats on the southern coastal plain. This account does not establish other behaviors or foods.
An extinction-risk assessment has not been added yet.