TER Nouvelle-Aquitaine is the regional rail network serving the region of Nouvelle-Aquitaine, southwestern France. It is operated by the French national railway company SNCF. It was formed in 2017 from the previous TER networks TER Aquitaine, TER Limousin and TER Poitou-Charentes, after the respective regions were merged.

Nouvelle-Aquitaine is the largest administrative region in France by area, spanning the west and southwest of Metropolitan France. The region was created in 2014 by the merging of Aquitaine, Limousin, and Poitou-Charentes in a territorial reform. Nouvelle-Aquitaine has an area of 84,035.7 km2 (32,446.4 sq mi) – more than 1⁄7 of Metropolitan France – and has a population of 6,033,952 as of 2020. The new region was established on 1 January 2016, following the regional elections in December 2015.