Air Canada Flight 621 slammed into a farm field in what is now Brampton on July 5, 1970, killing all 109 passengers and crew.
Family shared memories and laid white roses on a memorial plaque bearing the names of the victims of the crash.
Brampton Mayor Susan Fennell was in attendance along with the group of developers who put the garden in place. It has 109 stones and plaques with the names of the victims.
Some of those linked to the tragedy have spent years pressing for a permanent memorial site.
Lynda Fishman, who lost her mother and two younger sisters in the crash, said she has been living with a lifelong sentence of grief.