The hospital has received a $30-million gift from Peter Gilgan, the founder and CEO of Mattamy Homes.
Dr. Robert Howard, the hospital's president and CEO, said the donation will "transform" patient care at St. Michael's, where a new tower will be built in Gilgan's name.
Construction on the 17-storey Peter Gilgan Patient Care Tower could begin as soon as January.
It will take three years to complete. The hospital will remain open during that time.
The tower is being designed to meet the needs of critical care patients, which includes people undergoing emergency procedures as well as patients being treated in specialized units.
"With this new patient care tower, we will have the right space and the right equipment to provide the best care in Canada for critically ill patients," Howard said in a release.
Two new intensive care units will be established in the new tower, along with five state-of-the-art operating rooms. Officials say that all hospital rooms for in-patients will be single rooms.
Gilgan said he was pleased to help establish the new tower, so that staff at St. Michael's can do what they do best.
"I am so impressed with the quality, skill and professionalism of the doctors, nurses and health care workers at St. Mike's who day in and day out do incredible work with quite frankly not the best facilities, he said.