Rieux-Volvestre (before June 2009: Rieux;[3] French pronunciation: [ʁjø vɔlvɛstʁ]; Occitan: Rius) is a commune in Haute-Garonne department in southwestern France.

Rieux Cathedral, which is located here, was the seat of the Ancien Régime diocese of Rieux, created in 1317 and dissolved in 1790.

In 1560, Rieux-Volvestre was the site of the trial of Arnaud du Tilh, in the Martin Guerre case of imposture.

The commune of Rieux was renamed to Rieux-Volvestre in 2009, which is written by a decision.

The inhabitants of the commune are known as Rivois or Rivoises.