The girl was formally charged with 18 counts in connection with three incidents involving three victims.
The charges include human trafficking, abduction and sexual assault. She will be back in court Monday to have a date set for a bail hearing.
The suspect, who cannot be identified, is the second 15-year-old girl to be charged in the case.
Police allege they lured three females, between the ages of 13 and 17, to a home by posting messages on social media websites. The three victims were then allegedly forced to go to another location and perform sexual acts on men.
Ottawa police continue searching for a third suspect, a 17-year-old girl. (CFRA)