The area was first set aside as Bulga National Park in 1904. It comprised only 20 hectares. In 1909 Tarra Valley National Park was designated nearby. Over the years the two parks were gradually enlarged and then merged under the current name in 1986.
The deeply-incised river valleys of the park are dominated by wet sclerophyll tall open forest of mountain ash (Eucalyptus regnans), with an understorey of blackwood (Acacia melanoxylon), hazel pomaderris (Pomaderris aspera) and tree ferns (Dicksonia antarctica and Cyathea australis). Pockets of the park feature cool temperate rainforest, including Myrtle Beech Nothofagus cunninghamii. The ridges are dominated by open forest and low open forest of peppermint eucalypts and gums.
The tourist attractions include a large suspension bridge walk over the valley and many bushwalking tracks, and now provides visitors with an excellent example of the sort of forests which were once widespread in the area.