Known as Nutley Street, the state highway runs 2 miles (3.2 km) from U.S. Route 29 (US 29) and State Route 237 (SR 237) on the border between Oakton and Merrifield north to State Route 672 (Malcom Rd.)

Nutley Street continues south 0.51 miles (0.82 km) as a two-lane undivided road designated SR 10272 to US 50 (Arlington Boulevard).

SR 243 heads north as a six-lane divided highway through a cloverleaf interchange with I-66 just east of the Vienna station of the Washington Metro, which is the western terminus of the Orange Line that runs in the median of the Interstate from Vienna east to Arlington.

Access to the station is provided by the first intersection on either side of the I-66 interchange.

SR 243 continues into the town of Vienna as a four-lane divided boulevard that passes between residential neighborhoods before reaching its terminus at SR 123 (Maple Avenue) southwest of downtown Vienna.