Bobokulova was arrested in February as she waved the severed head of four-year-old Anastasia outside a Moscow metro station
A Moscow nanny on Monday pleaded guilty to murdering the four-year-old disabled child in her charge after brandishing the child's severed head on the street.
"I plead guilty; that's what she said," an interpreter said as Uzbek national Gyulchekhra Bobokulova went on trial, Interfax news agency reported.
In a chilling case, Bobokulova was arrested in February as she waved the severed head of four-year-old Anastasia outside a Moscow metro station.
The girl's headless body was later found in the family's flat, which had been set on fire.
The prosecutor at Moscow's Khoroshevsky district court read out the charges that 39-year-old Bobokulova had strangled Anastasia, who had cerebral palsy, and then beheaded her.
She then overturned an oil lamp that set the apartment ablaze and went outside carrying the child's head.
Witnesses said that the nanny paced for around 20 minutes on the street dressed in black, waving the severed head and threatening to blow herself up.
Russia's national television channels refused to cover the grisly killing in a controversial move that the Kremlin defended, saying the subject was "probably too monstrous to be shown on television."
Her trial is being covered by state television, however.
In March, at her first court appearance following her arrest, Bobokulova said that "it was what Allah ordered," speaking in broken Russian.
Bobokulova is being held in custody at a psychiatric hospital within Moscow's ageing Butyrka jail.
She has been diagnosed with paranoid schizophrenia and ruled not mentally capable. Prosecutors will ask for her to be incarcerated in a high-security psychiatric facility.
She is charged with the murder of a minor, which carries a maximum sentence of 25 years in prison, as well as arson and making a false report of an explosion.