The Vjosa (Albanian: [ˈvjɔsa]; indefinite form: Vjosë) or Aoös (Greek: Αώος) is a river in northwestern Greece and southwestern Albania.

Generally wild and unpolluted, the river is surrounded by the Vikos–Aoös National Park in Greece, and the Vjosa-Narta Protected Landscape near its mouth.

In antiquity it was called Aoös (Ἄωος, Ἀῶος, Ἀῷος) in Greek (e.g. in Eratosthenes' Geography[7]), and Aous in Latin.

The main cities and towns along the river are, in downstream order, Vovousa and Konitsa in Greece; and Çarshovë, Përmet, Këlcyrë, Tepelenë, Memaliaj, Selenicë and Novoselë in Albania.

The valley of the Vjosa has provided one of the most important natural routes between the mountainous interior of Epirus into southern Illyria and towards the Adriatic Sea.

[19] Hecataeus (550–476 BC) refers to the river as Aias (Ancient Greek: Αἴας), the name Anios (Ἄνιος) is used by Plutarch in Caesar,[20] while Polybius, Livy and Strabo use the term Aoös.

[27] Apollonia in Illyria was founded on the right bank near the mouth of the river around 600 BC by Greek colonists from Corinth and possibly Corcyra, who established a trading settlement on a largely abandoned coastal site by invitation of the local Illyrians.

The national park encompasses 126 square kilometres (31,135 acres) of mountainous terrain, with numerous rivers, lakes, caves, canyons, and coniferous and deciduous forest.

[18] The Vjosa's potential for hydropower has attracted developers to submit proposal to planning authorities for dam projects along the river and its tributaries.

By 2017, over 2000 dam projects had gained governmental approval on stretches of river throughout the Balkans, including the Vjosa's channel.

[39] In September 2020, Albanian prime minister Edi Rama announced that a protected area will be created around the Vjosa.

[2] In April 2021 a petition signed by Vjosa River scientists was delivered to Albanian president Ilir Meta.

[40] The scientists immediate concern is a plan by a Turkish-Albanian venture, Ayen ALB, to build a 50-metre high hydroelectric dam.