The facility ceased operations and was placed on care and maintenance in early 2016.
"The decision to close the New Brunswick potash facility reflects Nutrien's ability to increase potash production in Saskatchewan at a significantly lower operating and capital cost than resuming production in New Brunswick," officials said, adding that it will take an impairment charge of US$1.8 billion in the September quarter as a result of the closure.
The company recently completed its strategic review of its portfolio operations. It did not disclose the effective date of the closure.
Nutrien, which produces nitrogen and phosphate products in addition to potash, was formerly known as Potash Corp of Saskatchewan before merging with Agrium.