Francesca St-Pierre had been missing from a group home since Saturday.
Police said she was staying at the home for her own protection because she had been abused.
St-Pierre went out to run some errands on Saturday and never came back, police said. Youth protection authorities at the home notified police and a search was started.
Her body was discovered by cyclists on the bike path near the corner of Gouin Avenue and 24th Street Sunday evening.
Police said her body showed signs of violence.