Established in 2007, GSFM is an independent manager and distributor of investment strategies and products in Australia and New Zealand, with assets under management in excess of A$6bn (£3.7bn, $4.6bn, €4.1bn).
Current GSFM executives will retain a 20% stake in the company and the deal is expected to close on or around 15 November 2016.
The existing GSFM team will remain in place, and executives including chief executive Andrew McKinnon, head of distribution Damien McIntyre, and chief operating officer Peter Nichols will continue to manage all aspects of the company.
The company will continue to operate under the GSFM name.
Peter Anderson, chief executive of CI, said: "This acquisition aligns CI with a proven competitor in one of the world's fastest-growing pension markets, and is a significant new platform for CI as we expand our presence in global markets.
"CI has been looking for an opportunity to further expand outside Canada, and Australia was identified as an attractive market, with strong organic growth and a sophisticated investor base."
GSFM’s McKinnon said: "With this transaction, GSFM gains the backing of an accomplished asset management and distribution firm that is one of the largest investment fund companies in Canada.”