The Dusky Pigmy Rattlesnake occurs throughout Florida, excluding the Florida Keys. Outside of Florida, it occurs north to eastern North Carolina and west to eastern Texas and southern Missouri.

Common in lowland pine flatwoods, prairies, around lakes and ponds, and along the borders of many freshwater marshes and cypress swamps. Possibly the habitat in which Dusky Pigmy Rattlesnakes are most frequently encountered, at least in southern Florida, is the banks of canals running through marshes and prairies.

The Dusky Pigmy Rattlesnake has a reputation for protecting itself. Its bite, while usually not life threatening, can be painful and result in the loss of a digit. Some rare cases have be fatal. It feeds primarily on frogs and mice. The rattle sounds like an insect buzzing.