The doctor, who lives with his wife and runs a lab in Pitampura, is absconding. A case of rape has been registered, the police said. He is suspected to have abused other maids who worked for him too.
The NGO, Shakti Vahini, said it acted on an informant's tip and took the help of the police.
Rishi Kant, who works with the organisation, said that contrary to the pay and raises she was promised, the girl has just been paid Rs. 6,000 this year.
"The employer told her the money had been deposited in her mother's account," he said.
Reportedly brought to Delhi by an individual named Benoy and sold to a placement agency, this was the girl's first job. She was not allowed to go back home, not even when her father died.
The victim, who has studied till class four, has been produced before the child welfare committee and has been placed in a children's home.