Mattamy Homes founder and philanthropist Peter Gilgan donated $100 million towards the foundation, bringing the total fundraising total to $914 million.
"My hope is that it'll certainly encourage some folks to help move the needle," he said following the announcement, besting his previous record donation of $40 million. "I've been involved personally in some campaigns and I know they're tough, closing that last mile is always tough."
"A few of my friends have sent me notes and said how can I get involved, so hopefully we'll some action out of this."
The SickKids Foundation says the hospital will include a state of the art blood and marrow/cellular transplant therapy unit, as well as more critical care and in-patient units and mental health beds.
The fundraising campaign goes until 2022.
"We're where we thought we would be, still some heavy lifting," said CEO Ted Garrard.
Tanya Ploughman's daughter Marlow passed away at the age of nine after being a patient at SickKids, and her story was featured at the announcement.
"For somebody like Marlow who dealt with cancer, she needed every floor of this hospital to get through her treatment, not just the oncology floor, we literally were in every clinic over the five years we were here," Ploughman said. "The fact that this donation is getting us one step closer to where we need to be is just amazing."