Toronto-headquartered Onex will acquire 100% of the business for C$14.25 per share.
The wealth management firm will continue to be managed by its existing leadership team and retain its brand.
Gerry Schwartz, chairman and chief executive of Onex, said: “By combining Gluskin Sheff’s public securities investing platforms with Onex’ private equity and private debt platforms the clients of both firms will have greater investment options.”
The transaction is expected to close in the first half of 2019, subject to receipt of Gluskin Sheff shareholder and court approvals, required regulatory approvals and customary closing conditions.
Gluskin Sheff will have to pay a termination fee of C$13.3m to Onex if the transaction is not completed in certain circumstances, including if the transaction is not completed as a result of a superior proposal.
Jeff Moody, president and chief executive of Gluskin Sheff, said: “Onex is the ideal partner for us and our clients.
“We have a strong cultural fit and a like-minded approach to investing and risk management, which includes financial alignment between our teams and our investors.
“This partnership will provide us with the resources to better serve all of our clients and expand our product offerings with alternative investment strategies.”
Gluskin Sheff was founded in 1984 and serves high net worth private clients and institutional investors.
It has around C$8bn in assets under management – made up of 89% of high net worth clients.
In addition to its Toronto office, Onex has a presence in New York, New Jersey and London.