State Route 321 (SR 321) is a north–south state highway located entirely in Hamilton County in southeastern Tennessee.

From the Georgia state line and the northern terminus of Georgia State Route 151, SR 321 begins a northerly course to intersect State Routes 320 and 317, the latter of which is located in Collegedale.

Its northern terminus is at a junction with US 11/64 and SR 2 in Ooltewah.

It is known as Ooltewah Ringgold Road for the entirety of its length.

[2][3] The entire route is in Hamilton County.