The player is yet to agree personal terms, which are not expected to be an issue, but the agreement marks significant progress in West Ham’s drawn out centre-forward search.
Scamacca scored 16 goals in 36 league appearances for Sassuolo last term, making his Italy debut in September and featuring in the side that drew 0-0 with England at Molineux last month.
David Moyes is desperate to bring in competition for Michail Antonio, who is currently his only senior striker, with Andriy Yarmolenko, employed as a makeshift deputy last term, having left the club at the end of his contract.
Chelsea striker Armando Broja had been David Moyes’ No1 target but the club have been exploring alternative options, with uncertainty over whether or not the Albanian striker will leave Stamford Bridge this summer.
“We have bids in for players and we’re trying to get them in,” Moyes said after a 3-1 defeat to Rangers earlier this week.
“Getting them in at the moment is seeming quite difficult but by watching what I’ve seen in the opening games we need to add very quickly to the squad of players we’ve got.
“I hope [losing] comes as a good thing having a wake-up call, but I thought it was a good pre-season last year when we won all the games.
“You want to win the games and you want to go in [to the season] in good form. We certainly need to make a lot of changes and do something different, that’s for sure.”