[3] However, most authors today agree that the word came from the Innu root "Pessamit", meaning of "place where there are leeches or lampreys or sea eels".

The Innu and Oblate missionaries used Betsiamites, whereas Bersimis was preferred by Admiral Henry Wolsey Bayfield during his hydrographic surveys of the St. Lawrence and by the Hudson's Bay Company.

On the east side in the Innu village, the post office opened as Notre-Dame-de-Betshiamits in 1881, renamed to Bersimis in 1898 until 1919, and then took the name Betsiamites when demanded by the people.

Early in the 17th century, Samuel de Champlain reported the presence of an Innu village on the North Shore of the Saint Lawrence that he identified as Sauvages Bersiamiste on his map of 1632.

[6] In 1845, the registers of the Notre-Dame-de-Betshiamits Mission opened and a few years later in 1849, the Innu began to clear the site of present village in order to build a chapel.

But the formation of the reserve hardly affected the Innu because, for many years thereafter, most families remained nomadic and would spend almost all of their lives in the forest, hunting for caribou, beaver, and bear, as well as hare and partridge to supplement their diet.

[3][5] Private dwellings occupied by usual residents (2021): 822 (total dwellings: 841)[2] Mother tongue (2021):[2] Registered population of band members, as of May 2024:[9] The largest employer on the reserve is the band council, followed by Société d'aménagement et de développement forestier de Betsiamites, a forestry corporation that is managing the logging activities in the forests making up a large portion of the reserve's territory.