 Brilliant is in northeastern Wells Township, along the Ohio River south of Steubenville.Ohio State Route 7, a four-lane freeway, passes through the southeast side of the community, leading north (upriver) to Steubenville and south to Bridgeport, across the river from Wheeling, West Virginia.According to the 2010 census, the Brilliant CDP has a total area of , of which (or 98.87%) are land and (or 0.56%) are water.