Luis Polanco, 26, was arrested on the 4600 block of Industrial Street.
Police said Polanco began committing sexual offenses against a female relative living in the same residence beginning when the girl was 6 until she was 11. Polanco is 10 years older than the victim.
Simi Valley Police began investigating the case on August 4.
Polanco was arrested on charges of committing lewd acts upon a child and oral copulation of a person under 14 years old. Polanco is an undocumented Guatemalan citizen.
Anyone with information regarding Polanco or any of these crimes is asked to call the Violent Crimes Section Detectives at (805) 583-6248.