Authorities say Theodore Fernandes, a 50-year-old resident of Fontana, was taken into custody on Tuesday on 20 counts of sex-related crimes.
The investigation into the allegations began in February, but police say it took several months for an arrest due to the complexity of the case.
No further details were released on the incident to protect the victim's identity. The victim is now an adult.
Fernandes is being held at the West Valley Detention Center on $2 million bail.
Authorities do not believe there are other victims. Anyone with information is urged to call the Fontana Police Department at (909) 350-7740.