The river flows generally northwest, joined by forty tributaries that drain the Blackbraes National Park including, from source to mouth, the Styx, Percy, Robertson, Langdon, Little, and Einasleigh rivers and numerous creeks.

[2] The Gilbert River is a seasonal stream and discharge can vary greatly depending on the intensity of the monsoon.

[citation needed] Most of the basin is natural grassland used for grazing cattle at the extremely low densities permissible with the very low nutritive qualities of the feed available: the population is no more than one thousand or one person for over 40 square kilometres (15 sq mi).

In the upper reaches soils are more fertile red cracking clays but erode too easily under the erratic rainfall for cropping to be a likely prospect even with groundwater available.

[7] The river was named in July 1845 by Ludwig Leichhardt in honour of the naturalist John Gilbert who was killed two weeks earlier in an engagement with an Aboriginal group near the Gulf of Carpentaria coast.