L'Île-Rousse is a commune situated in the Haute-Corse department on the island of Corsica, France. Located in the northwest of the island, it occupies a bay bounded by rocky islets of red porphyry to the northwest and a white sand beach to the south. It stands as one of only three communes in the department retaining a French name, distinguishing it from others that have preserved their Italian or Corsican designations despite nationalist demands for linguistic uniformity.

The town was founded in 1758 by Pasquale Paoli to establish a port independent of Genoese control, which held nearby Calvi. Originally named Isola Rossa due to the reddish color of the rocky islet serving as a natural harbor, it developed from earlier settlements dating back to ancient times and Roman rule. The fort protecting the port was authorized in 1765, marking the formal birth of the modern settlement.

The old town features paved streets oriented north-south, with historic names honoring figures like Pasquale Paoli and Napoleon. Key landmarks include the covered market with twenty-one columns, the Église de l'Immaculée Conception de Marie on Place Paoli, and the Église Notre-Dame de la Miséricorde near an old Franciscan convent. The area also contains a Genoese tower and a small lighthouse of Piétra operating since 1857.

Visitors are drawn to the town's harmonious blend of old and new, shaded by century-old plane trees in the central square. The community engages in local traditions such as playing pétanque under date palms planted in 1890. The weekly market in the Greek-style hall offers local goods, while the nearby beaches provide family-friendly swimming opportunities with shallow waters accessible from the city center.

The commune had a population of 3,231 as of 2023. Its economy benefits from tourism and its role as a ferry hub connecting to Marseille, Nice, Toulon, and Savona. Accessible by train via the Chemin de Fer du Corse or by car through routes from Bastia and Calvi, L'Île-Rousse experiences a cold semi-arid climate with an average annual temperature of 16.9 °C.