The area was declared a wildlife sanctuary on 5 December 1969, and was upgraded to a national park on 4 January 1993 with land area of . However the park was regazetted in 2004 and the original park was reduced to . In 1991, Bundala became the first site in Sri Lanka to be designated a Ramsar wetland. In 2005, Bundala was declared a Man and Biosphere Reserve by UNESCO. In January 2006, an area adjacent to Bundala covering an area of was declared as the Wilmanna Sanctuary.