The people in the upper reaches of the Melawi speak Ot Danum and elsewhere along the river speak variants of the Malay language and the river banks are inhabited by the Malay and Dayak ethnic groups.

[3] A major town on the river is Nanga Pinoh, the capital of Melawi Regency.

The river meets the Kapuas in the town of Sintang.

[4] The river flows in the western area of Borneo with a predominantly tropical rainforest climate (designated as Af in the Köppen-Geiger climate classification).

The warmest month is May, when the average temperature is around 24 °C, and the coldest is February, at 22 °C.