Police said that the underage girl said in her complaint that the unidentified person took her away from the Navjeevan Camp Park in Govindpuri area on Monday night.
"The girl was left near her house around 10 pm. She narrated her ordeal to her mother, who complained to the police. A case was registered under the Protection of Children from Sexual Offences Act," Deputy Commissioner of Police Romil Banniya said.
"A medical examination at the All India Institute of Medical Sciences corroborated the girl's statement," Mr Banniya said.
Police are examining closed-circuit television footage from the area.
Based on early investigation, the crime appeared to have been committed in a planned manner since the accused had smeared his face and clothes with colour to hide his identity.
On Saturday, a 26-year-old woman had to jump from a 20-feet-high balcony in east Delhi to escape five men who allegedly raped her for hours, police said. The injured woman, a mother of two, walked on the streets without a shred of clothing, begging for help but no one came to her rescue, she told the police. All accused have been arrested.