Lake Iseo or Iseo lake (US: ee-ZAY-oh; Italian: Lago d'Iseo Italian pronunciation: [ˈlaːɡo diˈzɛːo]; Eastern Lombard: Lach d'Izé), also known as Sebino (Italian: [seˈbiːno]; Latin: Sebinus), is the fourth largest lake in Lombardy, Italy, fed by the Oglio River.

It is in the north of the country in the Val Camonica area, near the cities of Brescia and Bergamo. The lake is almost equally divided between the provinces of Bergamo and Brescia. Northern Italy is known for its heavily industrialised towns and in between there are several natural lakes. Lake Iseo retains its natural environment, with its lush green mountains surrounding the crystal clear lake.

There are several medieval towns around the lake, the largest being Iseo and Sarnico. A notable tourism sector has emerged. A road has been carved into the side of the mountains that circumnavigates the entire lake. In the middle of the lake there are Montisola island, Loreto isle and San Paolo isle (which compound the Monte Isola municipality). There is easy access via the regular running lake ferries.

The Floating Piers, an art installation by Christo and Jeanne-Claude (made of a series of walkways), was open to the public at Lake Iseo for 16 days in June and July 2016.

Since 2018, the northern portion of the lake (called Alto Sebino) has been part of the UNESCO World Biosphere Reserve of "Valle Camonica - Alto Sebino".