THE shock discovery of a two-year-old's lifeless body in a Sydney home has led to a woman being charged with the toddler's murder.

The remains were found inside the bathroom of a home in the suburb of Miller in the city's south-west at lunchtime on Tuesday.

A family friend became worried after she had not seen the child or her mother for a few days.

When she entered the house, she discovered the child's body in the bathtub.
 

An investigation into the girl's death led police to a hospital in the Blue Mountains where they arrested a 36-year-old woman, Fairfax Media reports.

She is due to face court in Penrith on Wednesday.

A neighbour has told ABC how a woman knocked on her door early on Tuesday to ask if she had seen the family.

"She knocked on my door and asked me if I had seen them and I said I hadn't seen them in a while," she told ABC.

The woman asked if she could borrow a ladder.

"And next the street was full of police."