The smoky shrew is active year-round. It is dull grey in colour with lighter underparts and a long tail which is brown on top and yellowish underneath. During winter, its fur is grey. Its body is about 4.3 in in length including 1.6 in long tail and it weighs about 0.18 oz. Smoky shrews start mating in late March, and females give birth to their first litters in April or May, about 20 days after mating. They are stockier, longer, with larger ears and feet, and a relatively shorter tail than masked shrews which they resemble in the summer.

This animal is found near streams in cool damp deciduous and mixed woods. It makes extensive, solitary, burrows in the leaf litter on the forest floor or builds globular nests 3.9–5.9 in of plant materials under rocks. The smoky shrew rarely digs tunnels, instead it uses tunnels created by moles or other shrews. Its diet consists mainly of beetles, however other insects, earthworms, snails, small rodents and other soil dwelling invertebrates are also taken. It also consumes plant material to supplement its diet. Predators include owls, snakes, foxes, weasels, and mustelids.