The 41-year-old woman, who cannot be named, was accused of raping her eight-year-old daughter at her home at Donnybrook, north of Brisbane, between November 2005 and February 2006.
The mother pleaded not guilty this week in the Brisbane District Court to one count of rape.
During the trial the court was told the child allegedly saw her mother standing in the doorway of her room holding a sex toy, or what the child called a "fake boy thing".
The woman entered the room, pulled down the young girl's pants and inserted something into her vagina, the court heard.
The court was told the girl has been medically examined, but that the examination was inconclusive.
The jury returned a verdict of guilty this afternoon after retiring yesterday.
The woman will be sentenced tomorrow.