Naas South (Irish: An Nás Theas) is a barony in County Kildare, Ireland.

Naas South derives its name from the town of Naas (Irish Nás na Ríogh, "assembly-place of the kings").

Naas South barony is located in east County Kildare, containing part of the upper Liffey valley and the western foothills of the Wicklow Mountains.

These were part of the ancient lands of the Ó Broin (O'Byrnes) before the 13th century, retaken in the 14th.

This article related to the geography of County Kildare, Ireland is a stub.