The Uruguayan featured prominently in his nation's run to the final of the recent Under-20 World Cup and has put pen to paper on a five-year deal with the Spanish club.
The youngster is reported to have cost the Andalusians in the region of €2.5 million and was quick to express delight at making the switch to La Liga.
"I'm joining a great club and I think this is a great opportunity for me," he told the club's official website.
Cristoforo also insisted he is not arriving as a replacement for Chile international Gary Medel, who left to join Cardiff City earlier this month.
"I did not come to cover a position or to replace another player. Medel is a very good player. I can only promise to give my best to help the team.
"I don't like to define myself as a certain type of player, but some say I'm like Uruguay international Diego Perez. I will just try to give my best to help the team at any time and in any position on the field."
Sevilla kick off the new Liga campaign at home to Atletico Madrid on August 18.