Muir of Dinnet is a national nature reserve (NNR) situated close to the village of Dinnet in Aberdeenshire, Scotland. The reserve extends 1166 hectares from the River Dee to Culbean hill, and encompasses a wide range of habitats including dry heath, raised bog, woodland, and two lochs: Loch Kinord and Loch Davan. Muir of Dinnet was first declared a NNR in 1977 due to its value as a habitat for flora and fauna, and its important geomorphological features, the most striking of which is the Burn O'Vat. Muir of Dinnet is owned by Dinnet Estate and managed by NatureScot, who provide a visitor centre and a range of other facilities including waymarked paths and a car park. As of 2012 it was estimated that approximately 40,000 people visited Muir of Dinnet each year.

The national nature reserves (NNRs) of Scotland are areas of land or water designated under the Wildlife and Countryside Act 1981 as containing habitats and species of national importance. National nature reserves can be owned by public, private, community or voluntary organisations but must be managed to conserve their important habitats and species, as well as providing opportunities for the public to enjoy and engage with nature. There are currently 43 NNRs in Scotland, which cover 154,250 hectares (1,542.5 km2), or less than 1.5% of the land area of Scotland. They range in size from Corrieshalloch Gorge at 7 ha to Mar Lodge Estate, which covers 29,324 ha.