The 20-year-old had been set to join the Biancocelesti in January, but the move fell through following complications over the necessary paperwork.
But the Serie A side have now secured his signature on a five-year deal, with a fee of €8 million thought to have been agreed between the sides last month.
The negotiations involved in the deal have been drawn out though, due to the complicated involvement of third-party investors.
It has been reported that Santos will net €4 million from Anderson’s sale and 25 per cent of any future transfer fee for the midfielder, while Doyen Sports will be handed €3.8m for their share.
Anderson is a product of the Pexie’s youth academy and made his official first team debut aged 17 in October 2010.
The Brazil Under-20 international will now continue his career in the Italian capital, joining compatriots Hernanes, Ederson and Andre Dias at the Stadio Olimpico.
