The star-nosed mole is seldom far from bodies of water. It prefers wet soils in flood plains, swamps, meadows, and other openings near water. It is a good swimmer and diver, and may be active in water under ice in winter. It is more dependent on water in winter when the ground is frozen. It occasionally occurs in leaf mold on the floor of dense forests. Tunnels may be shallow or deep and may open at the ground surface or under water. The nest usually is placed in a hummock, under a stump or log, in humus among rotten tree roots, or in other areas above high water, often near a stream. Gestation lasts about 45 days. Parturition occurs in spring or early summer (late March-early August in central New York). Litter size is three to seven, with an average of five to six, with one litter per year. They sexually mature in 10 months. They may maintain the pair bond throughout the breeding season.

In some areas this species eats mainly aquatic invertebrates; benthic prey may constitute entire winter diet. Earthworms are abundant in the diet in some areas (Peterson and Yates 1980). It is active all year, and active day or night, but may be more active at night.

This species is primarily distributed in the northeastern United States and southeastern Canada, from Labrador, Quebec, and Nova Scotia westward to eastern North Dakota and southeastern Manitoba, and south to Minnesota, Wisconsin, Indiana, and Ohio, south in the Appalachians to the Great Smoky Mountains, and south along the Atlantic coast to southeastern Georgia and the northern edge of Florida. It ranges farther north than all other native mole species.

The range of this species includes several protected areas.