| Rivière-Koksoak | |
| Settlement Type: | Unorganized territory |
| Pushpin Map: | Canada Quebec |
| Pushpin Mapsize: | 197 |
| Coordinates: | 57.1667°N -89°W |
| Subdivision Type: | Country |
| Subdivision Type1: | Province |
| Subdivision Type2: | Region |
| Subdivision Name2: | Nord-du-Québec |
| Subdivision Type3: | TE |
| Subdivision Name3: | Kativik |
| Established Title1: | Constituted |
| Established Date1: | January 1, 1986 |
| Leader Title1: | Federal riding |
| Leader Name1: | Abitibi—Baie-James—Nunavik—Eeyou |
| Leader Title2: | Prov. riding |
| Leader Name2: | Duplessis and Ungava |
| Area Total Km2: | 346429.30 |
| Area Land Km2: | 307039.90 |
| Population Total: | 0 |
| Population As Of: | 2011 |
| Population Density Km2: | 0.0 |
| Population Blank1 Title: | Change (2006–11) |
| Population Blank1: | 100.0% |
| Population Blank2 Title: | Dwellings |
| Population Blank2: | 0 |
| Timezone: | EST |
| Utc Offset: | −5 |
| Timezone Dst: | EDT |
| Utc Offset Dst: | −4 |
Rivière-Koksoak is a very large unorganized territory in the Kativik Regional Government territory in the Nord-du-Québec region of Quebec. It is named after the Koksoak River.
It consists of nearly the entire eastern part of northernmost Quebec. Bordering it to the west is the other large unorganized territory in Kativik, Baie-d'Hudson.
Its population in the Canada 2011 Census was 0; enclaved within it, however, are various northern villages (i.e., Inuit communities) and one (uninhabited) Naskapi village municipality. In the 2006 census it had a population of 15.