Foggy Bottom–GWU uses a simple island platform layout: one platform with a track on each side. Track C1 carries eastbound trains to New Carrollton and Downtown Largo whilst track C2 is used by westbound trains to Vienna, Franconia–Springfield, and Ashburn.[6] As with all stations on the Metro, there are platform edge lights to warn passengers of incoming trains.
In 2008, WMATA installed red-colored LED lights at Foggy Bottom–GWU and other busy stations after a successful pilot at Gallery Place.[7] There is a 22 coffer "waffle vault" ceiling at Foggy Bottom–GWU as it was one of the first stations to be built in the system; later underground stations abandoned this design for a simpler concrete arch.
There is a single mezzanine located at the center of the platform.[8] Escalators from here allow passengers to descend to platform level or to the sole entrance and exit of the station at the northwestern corner of I and 23rd Streets.[9] A total of two elevators and six escalators (three between the street and mezzanine and three between the mezzanine and platform) are currently in use at the station.[10]