Lake Beyşehir (Türkçe. Beyşehir Gölü) is a large freshwater lake in Isparta and Konya provinces, southwestern part of Turkey. It is located at around . It has an area of 650.00 km² and is 45 km long and 20 km wide. It carries the same name as the principal urban center of its region, Beyşehir.
Water level in the lake often fluctuates. Lake Beyşehir is used for irrigation, although it is also a national park. There are thirty-two islets in varying sizes in the lake. Lake Beyşehir is also an important site for many bird species.