The Loch of Kirbister is a small, shallow, somewhat triangular-shaped loch located on Mainland Orkney, Scotland, in the parish of Orphir. It lies 5 mi (8.0 km) southwest of Kirkwall on cultivated land between two hills. There is a small (37 m (121 ft) by 19 m (62 ft)) turf-covered islet known as the Groundwater of Holm just off the eastern shore of the loch. The islet exhibits stone traces of an oval structure and a small projecting pier. The loch is a popular spot for trout fishing, and the Orkney Trout Fishing Association operates a hatchery at the Kirbister pumphouse located on the edge of the loch.

Mill Burn, the southern outflow from the loch, was used to power the 18th-century Kirbister Mill.

The loch was surveyed in 1903 by T.N. Johnston and R.C. Marshall and later charted as part of Sir John Murray's The Bathymetrical Survey of Fresh-Water Lochs of Scotland 1897-1909.