Europol says the victims were kept in "squalid conditions in caves" and intimidated with voodoo threats.
Gang members forced the women into sex work in order to pay off a 30,000 euro ($37,000; £26,000) debt.
Eighty-nine people, including a famous but as yet unnamed Nigerian DJ, have been arrested.
The DJ is said to have helped move victims to Spain and organise sexual exploitation across the country.
He was caught flying back into Spain after recording a music video.
