Taymouth Castle is situated to the north-east of the village of Kenmore, Perth and Kinross, in the Highlands of Scotland, in an estate which encompasses 450 acres (180 ha). It lies on the south bank of the River Tay, about 1 mile (1.6 km) from Loch Tay, in the heartland of the Grampian Mountains. Taymouth is bordered on two sides by mountain ranges, by Loch Tay on the third and by the confluence of the rivers Lyon and Tay on the fourth.

The River Tay is the longest river in Scotland and the seventh-longest in Great Britain. The Tay originates in western Scotland on the slopes of Ben Lui, then flows easterly across the Highlands, through Loch Dochart, Loch Iubhair and Loch Tay, then continues east through Strathtay, in the centre of Scotland, then southeasterly through Perth, where it becomes tidal, to its mouth at the Firth of Tay, south of Dundee. It is the largest river in the United Kingdom by measured discharge. Its catchment is approximately 2,000 square miles, the Tweed's is 1,500 sq mi (3,900 km2) and the Spey's is 1,097 sq mi (2,840 km2).