Berge Østenstad (born September 15, 1964) is a Norwegian chess player and Norway's sixth International Grandmaster. Østenstad plays for the chess club in Asker.

As of 2005, Østenstad has won more Norwegian Chess Championships than any other player, seven in total. He won in 1984, 1990, 1994, 1997, 1999, 2003 and 2004.

Østenstad gained the title of International Master in 1987. He achieved his first GM norm in Gausdal in 1990, his second in Biel in 1990 and the third in Gothenburg in 2003. His rating peaked the required 2500 in 1991. The Biel norm came after FIDE liberalized the requirements for GM norms by allowing them to be achieved before the tournament ended, and made these changes retroactive.