NC 121 begins at a partial interchange with I-587, also known as the John P. East Memorial Highway, in northeastern Greene County.

This portion of the road is located near the community of Fieldsboro and two and a half miles (4.0 km) northeast of the town of Walstonburg.

Just before the highway crosses into Pitt County, the concurrency ends and NC 121 heads northeast towards Farmville.

Another concurrency is formed as the two routes travel along West Wilson Street to the central business district of Farmville.

Farmland and small homes line the highway as it passes through the communities of Joyners Crossroads and California.

[7] In June 1932, the American Association of State Highway Officials (AASHO) approved the routing of US 258 which was run concurrently with NC 121 between Richlands and Kinston.