"[The court rules] to keep the Presnensky District Court's ruling unchanged", the judge said.
The blogger's lawyer said he intended to appeal the ruling to the European Court of Human Rights in Strasbourg.
Sinitsa has maintained his innocence and insists that his words were taken out of context.
On 31 July, Sinitsa posted on Twitter what prosecution has interpreted as a call to kill the children of police officers who dispersed unauthorised rallies in Moscow this summer. The blogger was arrested on 4 August and sentenced to five years in prison on extremism charges by a court.
The Russian blogger made his comment against the backdrop of unauthorised rallies that happened in Moscow during the summer in response to the local election commission barring several opposition candidates from running in the city council election. Several activists have received varying prison sentences for their participation in the rallies.