Tunø is a Danish island in the Kattegat, approximately 4 km west of the neighbouring island of Samsø. The island covers an area of and has 113 inhabitants, . It comes under the administration of Odder municipality. Tunø By is the only village on the island, with the hamlet of Løkkegårde as the second most populated area.
Tunø harbour, lies a little east of the town of Tunø By, and is protected by 2 piers. The marina here has room for approximately 170 boats. From the harbour there is a daily ferry service to and from the town of Hou, East Jutland.
Every summer Tunø hosts a popular music festival, Tunø Festival, attracting Danish and international artists alike. In 2011, Tunø Festival enjoyed its 25th anniversary.