In 1803, the Hudson's Bay Company founded Fort George, a trading post on the north shore which was relocated to the largest island at the mouth of La Grande River in 1837.

Fort George became a permanent village as the local Cree population abandoned their nomadic way of life in the early 20th century and settled nearby.

[6] In the mid-1970s, the construction of the James Bay hydro-electric project began, diverting upstream rivers into the La Grande watershed, increasing its flow significantly, resulting in erosion of Fort George Island (also called Governor's Island) and disruption to the formation of a solid ice cover in winter.

[7] In response, the Quebec Government built a new community on the mainland's south shore, relocating the population and some 200 houses to the new site in 1981.

Many Cree in Chisasibi engage in hunting, trapping, and fishing activities, but all catch is for local consumption.

[3] As of the 2021 census the population of Chisasibi comprises 4,305 Cree, 345 other First Nations, 240 Inuit, 10 Métis, and 245 non-native people.

[14] Chisasibi has a subarctic climate (Köppen Dfc), typical of the central latitudes of Quebec, with cold and snowy winters and mild, rainy summers.