A new species, Juncus snowii W. M. Knapp & R. Carter (Juncaceae), is described from two counties of the Altamaha grit, a sandstone formation in the coastal plain physiographic province of Georgia, U.S.A. This new species resembles other members of Juncus L. sect. Ozophyllum Dumort. but is readily distinguished by a combination of characters including its typically annual life history, diminutive habit, and small capsules and tepals. The type locality is an area of geologic interest that supports a unique assemblage of rare and endemic plant species. Color photographs are provided for the new species, as well as preliminary conservation status assessments using NatureServe criteria (Critically Imperiled with extinction [G1]) and IUCN Red List criteria (Vulnerable [VU D2]).