It rises on Ben More Assynt, a few miles from Ullapool on the west coast of Scotland, and drains into the North Sea via the Kyle of Sutherland.

[1] Firstly, this and other similar hydronyms may involve the element og, meaning "lively" (c.f River Ogwen, Wales), suffixed by the diminutive -ell.

[1] Secondly, Oykel may represent Pictish *ogel meaning "ridge",[1] although long rivers are rarely named after minor local features.

The A837 road runs along the river for most of its length, crossing it just above the junction with the Einig, about 6 miles (10 kilometres) west of Rosehall at Oykel Bridge.

In 1406, the Mackays defeated the Clan MacLeod of Lewis at the Battle of Tuiteam Tarbhach[2] on the north bank near the mouth of the Tutim Burn.