[2][3] It rises near Ballyhaunis, then flows generally west for 64 kilometres (40 mi), where it drains into Lough Mask.

[1][4] The river is the longest tributary of Lough Mask and it drains 320 square kilometres of south Mayo.

It meanders in serpentine coils beside the R331 road, passing Taugheen, from where it begins its southwesterly descent to Hollymount.

From there, the river winds in broad loops before descending southwestwards into Ballinrobe (Irish: Baile an Róba, meaning 'town of the Robe').

The Robe empties into Lough Mask, four kilometres west of Ballinrobe, near Cushlough (Irish: Cois Loch, meaning 'beside the lake').