Ustaritz (Basque:Uztaritze) is a town in the traditional Basque province of Labourd, now a commune in the Pyrénées-Atlantiques department in south-western France. It is located on the river Nive some 13 kilometres (8.1 mi) inland from Bayonne.

Ustaritz was the location of the assembly of local Basque leaders before the French Revolution.