The river was named by Sir Thomas Button, a Welsh explorer from St. Lythans, Glamorganshire, who wintered at its mouth in 1612, after Robert Nelson, a ship's master who died there.
At that time, the Cree people who lived along its banks called it Powinigow or Powinini-gow, which may have meant "the Rapid Strangers' river".
The area was fought over for the fur trade, though the Hayes River, whose mouth is near the Nelson's, became the main route inland.

Fort Nelson, a historic Hudson's Bay Company trading post, was at the mouth of the Nelson River at Hudson Bay and was a key trading post in the early 18th century.
After his pivotal role in establishing the Hudson's Bay Company, Pierre Esprit Radisson, noted French explorer, was chief director of trade at Fort Nelson during one of his sustained periods of service to England.
Today, Fort Nelson no longer exists.
Port Nelson, the abandoned shipping port, remains on the opposite side of the river mouth on Hudson Bay.

The Nelson River's huge volume and long drop make it useful for generating hydroelectricity.
Flooding caused by damming of the river has provoked bitter disputes with First Nations in the past although the Northern Flood Agreement was created in the 1970s to help offset the damages caused by flooding.

"Travelling up the Nelson River, it’s easy to see the impacts of hydro development.
The once-pristine water is now silty and not to be trusted for drinking.
Trees fall into the river everywhere along the shore, thanks to erosion caused by constantly fluctuating water levels.
Ancient graves are being exposed, and sacred sites are now under water.
What was once a highway for hunters is now dangerous to travel in winter, as the location of ice pockets created by flooding and retreating water cannot be predicted.
A river that was once the basis for life has become deadly."
Peter Kulchyski 2012
The river was named by Sir Thomas Button, a Welsh explorer from St. Lythans, Glamorganshire, who wintered at its mouth in 1612, after Robert Nelson, a ship's master who died there. At that time, the Cree people who lived along its banks called it Powinigow or Powinini-gow, which may have meant "the Rapid Strangers' river". The area was fought over for the fur trade, though the Hayes River, whose mouth is near the Nelson's, became the main route inland.
Fort Nelson, a historic Hudson's Bay Company trading post, was at the mouth of the Nelson River at Hudson Bay and was a key trading post in the early 18th century. After his pivotal role in establishing the Hudson's Bay Company, Pierre Esprit Radisson, noted French explorer, was chief director of trade at Fort Nelson during one of his sustained periods of service to England. Today, Fort Nelson no longer exists. Port Nelson, the abandoned shipping port, remains on the opposite side of the river mouth on Hudson Bay.
The Nelson River's huge volume and long drop make it useful for generating hydroelectricity. Flooding caused by damming of the river has provoked bitter disputes with First Nations in the past although the Northern Flood Agreement was created in the 1970s to help offset the damages caused by flooding.
"Travelling up the Nelson River, it’s easy to see the impacts of hydro development. The once-pristine water is now silty and not to be trusted for drinking. Trees fall into the river everywhere along the shore, thanks to erosion caused by constantly fluctuating water levels. Ancient graves are being exposed, and sacred sites are now under water. What was once a highway for hunters is now dangerous to travel in winter, as the location of ice pockets created by flooding and retreating water cannot be predicted. A river that was once the basis for life has become deadly." Peter Kulchyski 2012
Nelson River