Paolo Gabriele was arrested in May after police found confidential documents at his Vatican flat.
He has been charged with aggravated theft, including stealing a 100,000-euro (£78,000) cheque, while a computer analyst faces complicity charges.
Mr Gabriele admitted he was the source of leaked letters published in a controversial book by an Italian investigative journalist in May.
The bestseller, entitled His Holiness, revealed private correspondence between the Pope and his personal secretary discussing corruption and malpractice among Vatican administrators.
The Vatican called the book "criminal" and vowed to take legal action against the author, publisher, and whoever leaked the documents.
Mr Gabriele told investigators he acted because he saw "evil and corruption everywhere in the church" while the pope was "not sufficiently informed".