Gabriele, 45, was held in solitary confinement in a Vatican cell for almost two months before being granted house arrest.
Claudio Sciarpelletti, a computer expert working at the Vatican Secretariat of State, also was indicted for aiding and abetting Gabriele, but according to the Vatican chief spokesman, the Rev. Federico Lombardi, he played a minor role and would probably incur a light sentence if convicted.
Gabriele, meanwhile, faces a six-year jail term, which could be lengthened to eight years if judges find one or more "aggravating factors."
A raid at the butler's Vatican apartment revealed he had amassed a large amount of papal documents, including a check made out to Benedict for 100,000 euros ($123,000).
Both men will be tried by a court composed of three lay Vatican judges, who are also law professors at Italian universities. The earliest the trial would start would be late next month.
During the investigation, Gabriele told judges that he leaked the pope's documents to journalist Gianluigi Nuzzi, who then published them in the best-selling book Sua Santita (His Holiness) with the aim of "bringing the church back on the right track" through a media "shock."
He said he was convinced that "evil and corruption" were "everywhere" in the church and that the pope was not adequately informed. "In a certain sense, I felt as an infiltrator ... of the Holy Spirit," he told prosecutors June 5.
Two psychiatrists visited Gabriele on the Vatican's behalf during the investigation. While they found the butler of sound mind and capable of standing trial, they also reported signs of paranoia and warned that he could be easily manipulated.
The indictment hints that Gabriele, besides copying confidential letters and memos from the pope's personal office, might have also been receiving documents by other people inside the Vatican.
A sealed letter marked "Personal P. Gabriele" was found in Sciarpelletti's desk at the Secretariat of State. According to Sciarpelletti himself, it had been given to him by an unnamed source, identified only as "W" in the indictment.
Vatican prosecutor Nicola Picardi stressed that his investigation was only "partially completed," leaving the door open to further developments. A second, parallel investigation by an ad hoc cardinals' commission created by the pope has completed its work but its findings are still unknown.