The 23-12 months-old will reportedly price the Hammers an preliminary £30.Five million ($37 million) with a similarly £five million in accessories. Scamacca had been connected with Juventus and Paris Saint-Germain after scoring sixteen goals in 36 matches in Serie A last season.
"I am without a doubt excited to sign up for West Ham. I've waited a long term for this second. It's been a dream to play within the Premier League. I sense like West Ham is an appropriate team for me. They showed they absolutely desired me and once I spoke to the supervisor there was an on the spot expertise", said Scamacca.
West Ham had been in the market for attacking reinforcements to lighten the weight on Michail Antonio up the front.
"We've been looking to add extra energy to our attacking options for some time, so we're overjoyed to have got Gianluca in", said West Ham boss David Moyes.
"He comes actually well endorsed and we're looking ahead to operating with him. He's a young centre-ahead with a without a doubt bright future in advance of him", stated he.
Scamacca should make his debut towards English champions Manchester City on the hole weekend of the Premier League season on August 7.
