The 19-year-old striker will begin his four-month loan period when he returns fron a trip to Austria with the Italy Under-21 team, and trains for the first time with Glenn Roeder's squad.
Rooney: "Giuseppe is a great player and one to watch out for. I see him every day in training and he has really impressed me. His touch, feel of the ball and awareness are nothing short of brilliant.
"He is perhaps the best finisher at Manchester United and he will only get better.
"I have talked to the likes of Michael Carrick and Joe Cole about the way Glenn Roeder brought them through at West Ham and the feeling at Old Trafford is that Giuseppe is in good hands with Newcastle."