|Hudson Bay drainage basin|
|Countries||Canada, United States|
|Highest point||Mount Assiniboine|
|- location||Canadian Rockies|
The Hudson Bay drainage basin is the drainage basin in northern North America where surface water empties into Hudson Bay and adjoining waters. Spanning an area of about 3,861,400 square kilometres (1,490,900 sq mi),  the basin is almost totally in Canada (spanning parts of the Prairies, central and northern Canada), with a small portion in the United States (in Montana, the Dakotas, and Minnesota). The watershed's headwaters are in part on the Continental Divide of the Americas, and the watershed's connection to the Labrador Sea is at the Hudson Strait's mouth between Resolution Island in the Qikiqtaaluk Region and Cape Chidley on the Labrador Peninsula.  On the Continental Divide the basin is bounded at Triple Divide Peak to the south, and Snow Dome to the north.
Hudson Bay is often considered part of the Arctic Ocean. For example, the International Hydrographic Organization (in its current unapproved working edition only  of Limits of Oceans and Seas) defines the Hudson Bay, with its outlet extending from 62.5 to 66.5 degrees north (just a few miles south of the Arctic Circle) as being part of the Arctic Ocean, specifically "Arctic Ocean Subdivision 9.11." Other authorities include it, in part because of its greater water budget connection, with the Atlantic Ocean.  
The Hudson Bay drainage basin coincides almost completely with the former territory Rupert's Land, claimed by the Hudson's Bay Company in the 17th century, and an ideal area for the early fur trade in northern and central North America.
- "Canada Drainage Basins". The National Atlas of Canada, 5th edition. Natural Resources Canada. 1985. Retrieved 24 November 2010.
- Limits of Oceans and Seas (PDF), 1953, retrieved 2010-11-26
- "IHO Publication S-23 Limits of Oceans and Seas; Chapter 9: Arctic Ocean". International Hydrographic Organization. 2002. Retrieved 2017-07-01.
- Earle, Sylvia A.; Glover, Linda K. (2008). Ocean: An Illustrated Atlas. National Geographic Society. p. 112. ISBN 978-1-4262-0319-0. Retrieved 26 November 2010.
- Lewis, Edward Lyn; Jones, E. Peter; et al., eds. (2000). The Freshwater Budget of the Arctic Ocean. Springer. pp. 101, 282–283. ISBN 978-0-7923-6439-9. Retrieved 26 November 2010.