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 euros 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," Cristoforo told the club's official website.
"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," Cristoforo said. "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 kicks off the new Liga campaign at home against Atletico Madrid on Aug. 18.