That's double the $1.97 billion bought in 2014 and more than the $2 billion in acquisitions in 2007.
The real estate arms of pension funds such as the Canada Pension Plan Investment Board, Caisse de dépôt et placement du Québec and the Ontario Municipal Employees Retirement System are among the biggest investors, with $581 billion in New York properties under management.
Despite the high prices of Manhattan properties, "there's an understanding that there's always somebody who wants to buy an asset in New York," Real Capital's Joe Costello told Bloomberg.
Canada's pension plans have large pools of capital and are looking for long-term investments that have potential for stable return, either from operating income or from capital growth.
Ivanhoe Cambridge Inc., the real estate arm of the Caisse, owns about $7 billion in U.S. properties, including iconic buildings such as the headquarters for Robert Murdoch's 21st Century Fox.
It also was part of a consortium that paid $2.2 billion in January for 1095 Avenue of the Americas, bought from the Blackstone Group.
Canadian companies are also involved in developing Manhattan properties.
Oxford Properties Group Inc., a unit of OMERS, is part of a group behind an ambitious redevelopment on the New York waterfront called Hudson Yards that could ultimately create 17 million square feet of commercial and residential space.
Brookfield Property Partners, which owns an extensive global portfolio, is building an office complex near the 9/11 memorial called Manhattan West.
Canadian property companies and pension funds have been the largest buyers of Manhattan property in the past decade, followed by United Arab Emirates, China and Israel.
Capital pools from other countries, including Norway's sovereign-wealth fund, which owns $4.9 billion US in property, and the Qatar Investment Authority, which owns $4.5 billion US, have also bought into real estate, but not on the same scale as Canada.
Since hitting a low in 2010 in the wake of the financial crisis, U.S. commercial property has more than doubled in price. In Manhattan real estate has been particularly strong, with residential property at a premium.
The strong U.S. dollar makes the investment even more promising for Canadian buyers as other investments, such as bonds and stocks that can have disappointing returns.
ALSO ON HUFFPOST: