The Cairngorms (Scottish Gaelic: Am Monadh Ruadh) are a mountain range in the eastern Highlands of Scotland closely associated with the mountain Cairn Gorm. The Cairngorms became part of Scotland's second national park (the Cairngorms National Park) on 1 September 2003. Although the Cairngorms give their name to, and are at the heart of, the Cairngorms National Park, they only form one part of the national park, alongside other hill ranges such as the Angus Glens and the Monadhliath, and lower areas like Strathspey.

The Cairngorms consists of high plateaux at about 1,000–1,200 m (3,300–3,900 ft) above sea level, above which domed summits (the eroded stumps of once much higher mountains ) rise to around 1,300 m (4,300 ft). Many of the summits have tors, free-standing rock outcrops that stand on top of the boulder-strewn landscape. In places, the edges of the plateau form steep cliffs of granite and they are excellent for skiing, rock climbing and ice climbing. The Cairngorms form an arctic-alpine mountain environment, with tundra-like characteristics and long-lasting snow patches. This area is home to bird species such as ptarmigan, dotterel, snow bunting, curlew and red grouse, as well as mammals such as mountain hare. The plateau also supports Britain's only herd of reindeer (albeit semi-domesticated). Surrounding the central massif are many remnants of the Caledonian forest in straths and glens of the Rivers Spey and Dee. These forests support many species that are rare elsewhere in Britain, including red squirrels, pine marten, wood ants, Scottish crossbill, capercaillie and crested tit.

There are no glaciers, but snow can fall in any month of the year, and snow patches usually persist all summer; for snow and ice climbing, the area is the most dependable in Britain. The mountains are also popular for hill-walking, ski touring and climbing, and there are three alpine ski centres in the range, at Cairn Gorm, The Lecht and Glenshee.

The range lies in the Scottish council areas of Aberdeenshire, Moray and Highland, and within the counties of Aberdeenshire, Inverness-shire and Banffshire.