This small rattlesnake is endemic to San Lorenzo Sur Island located in the Gulf of California near Baja California. Its habitat primarily includes rocky areas with arroyo bottoms, dunes, and cavities formed by large rocks and boulders. The San Lorenzo Island rattlesnake has also been recorded in trees on the island, perhaps leading to a more semi-arboreal lifestyle and the addition of birds to its diet. This subspecies is notably smaller than Crotalus ruber populations from the mainland.

The San Lorenzo Island rattlesnake often loses its rattle after a shed, and most of the individuals do not have a rattle at all. This is due to a lack of structure in the proximal rattle segment, likely an adaptation to an island environment over time.