Detectives were called to a luxury Mermaid Beach apartment complex just after 8am.
Paramedics said the girl, believed to be around two years old, was found dead inside.
A crime scene was declared while police combed through the building and left with paper bags.
Read Related Also: Rapper Fredo Bang Welcomes Son With Married YouTube Couple Annie & Sevyn Buffins
One neighbour told 9News there was “not too much commotion” but guessed there were around 10 police officers on the street.
Police have indicated the investigation could be a lengthy.
