The real estate arm of the Caisse de depot et placement du Quebec also said it plans to invest more than $100 million in a revitalization program for the property.
The deal, which will consolidate Ivanhoe Cambridge's ownership of Place Ville Marie, will require approval by the federal Competition Bureau.
Place Ville Marie has five towers and a shopping promenade. It is directly linked to Montreal's underground transit system and pedestrian network.
"We are very proud to seize this new opportunity; this significant investment in Montreal will be the anchor of a broad plan we will implement this fall," Ivanhoe Cambridge chairman and chief executive Daniel Fournier said in a statement.
"Place Ville Marie is more than just a building; it is at the real estate core of the city and, more than ever, the cornerstone of our Montreal property portfolio."
AIMCo said in April it was looking to sell its stake of in the business complex after what it described as a regular review of its assets.
AIMCo invests on behalf of 26 pension, endowment and government funds in Alberta, including the Alberta Heritage Savings Trust Fund.