The Luy de Béarn (French pronunciation: [lɥi də beaʁn], literally Luy of Béarn; Occitan: Lui de Bearn) is a left tributary of the Luy, in the Southwest of France. It is 76.6 km (47.6 mi) long.

The source of the Luy de Béarn is at the base of the plateau of Ger, east of Pau. It flows north-west through the Chalosse region and joins the Luy de France to form the Luy below the castle of Gaujacq.

The Luy de Béarn flows through the following departments and towns:

• Pyrénées-Atlantiques: Montardon, Sauvagnon, Sault-de-Navailles
• Landes: Amou

• (L) Aïgue Longue, from the moor of Pont-Long in the north of Pau.
• (L) Uzan, in Uzan, also from Pont-Long.
• (L) Aubin.
• (L) Oursoû, from the nord of Orthez.