Sydney mother pays tribute to dead toddler

The mother of a toddler who died after being left in a car in Sydney's west has paid tribute to her young son online.

The 22-month-old was found unresponsive inside a car at the front of a Chester Hill home on Sunday afternoon, according to NSW Police.

Paramedics were unable to revive him and he was pronounced dead at the scene.

The child's mother, Samantha Rowlands, on Monday uploaded a photograph of her son to Facebook with the caption "my baby".

"Rest In Peace beautiful angel we love u," one woman replied.

Detectives were told the child was found inside a car at the front of the residence by family members after he couldn't be located inside the home.

The boy, said to be a twin and the youngest of six children, was reportedly left in the care of someone else while his mother was out.

His grandmother, who lives at the house, was taken to hospital suffering from shock, News Corp Australia reported.

Police are preparing a report for the coroner.