The girl's parents, who are daily wage labourers, were not at home last night when the incident occurred, police said.
The 42-year-old man entered the house when the girl was asleep and sexually abused her, they said.
Neighbours rushed to the spot on hearing her screams, caught hold of the man and handed him over to police.
The girl has been hospitalised, police said.
Inside Photos: Gauri Khan, Shweta Bachchan, Aishwarya Rai go glam!
Photos: Malaika Arora spotted at a salon in Bandra
Inside Photos: Malaika Arora, Kareena Kapoor Khan party with Isha Ambani
Photos: Deepika Padukone with father Prakash at Mumbai airport
Sachin Tendulkar, son Arjun join Aaditya Thackeray for cleanliness drive in Bandra