Turnbull had been writing and reporting for the Star since 1990, where she had been a longtime member of the Life section at the time of her death.
The Star tweeted that Turnbull had died Sunday.
As a teenager, Turnbull was paralyzed from the neck down in a high-profile 1983 shooting that occurred at a convenience store she was working at in Mississauga, Ont.
The Star's features editor Janet Hurley sent an email to employees on Sunday informing them of her passing.
"If there ever was an example of someone who didn't let life's challenges get in the way of living that life as fully as possible, it was Barb," the email said.
"And many others — for organ recipients to those with disabilities — have had better lives due to her sheer determination."
A number of her colleagues tweeted about what her loss meant to them.
Star reporter Mitch Potter tweeted that he was "gutted" by her passing, calling Turnbull "the inspirational light" of the paper's newsroom.
Former lieutenant-governor David Onley tweeted he was "deeply saddened" to hear of her death.
"She was a courageous person who inspired us all. May she rest in peace," Onley said.
Her autobiography, Looking in the Mirror, was published in 1997.