It originates in the jungle 100 or more miles southeast of Paraibo and meanders northwest until it receives the meandering Cottica River from the east and then runs west until it joins the north-flowing Suriname River estuary at Nieuw Amsterdam about 10 miles below Paraíba.

Here, after some 30 kilometres (19 mi) the combined rivers enter the Atlantic Ocean.

The Commewijne was important historically for navigation: ocean-going ships navigated the river huge barges with bauxite were transported from Moengo in the east to the confluence with the Surinam river and from there traveled southward via Paramaribo to the Paranam refinery and to Trinidad and the USA.

Floats with tropical hardwood were also brought to Paramaribo, the capital of Suriname.

Today's name "Commewijne" is probably derived from Arawak words "kama" (tapir) and "wini" (water/river).