The American international sealed a move to the Black Cats earlier this week in a £6m deal from Dutch side AZ Alkmaar.
Di Canio told the club's official website: "I'm really pleased because a new arrival can benefit the squad and also individuals because there is competition up front.
"Altidore is one of the top strikers in Europe. He only joined us on Tuesday but I'm very happy, curious and excited because I have a very good attacking side at the moment."
Sunderland begin their Premier League campaign at home to Fulham on August 17.