The community is located in southern Fentress County on the
Cumberland Plateau. The settled part is located on high ground in the center of the CDP, with elevations ranging from . The west side of the CDP drops into the gorge of the East Fork of the
Obey River, with a bottom elevation of , and the east side follows the valley of the North Prong of
Clear Fork, with an elevation of . Both rivers are part of the
Cumberland River watershed.
U.S. Route 127 is the main road through the community, leading north to
Jamestown, the Fentress County seat, and south to
Clarkrange.
Tennessee State Route 85 forms the southwestern edge of the CDP, dropping by switchbacks into the gorge of the East Fork of the Obey and leading to
Livingston. According to the
U.S. Census Bureau, the Grimsley CDP has an area of , all of it land. == Demographics ==