The wing-back has been on loan at Borussia Dortmund for the past two seasons, and has scored nine goals this season.
Lucien Favre had been keen on holding onto the 21-year-old but it appears that Inter have swooped with a bid of €40 million + €5 million in add ons.
Fabrizio Romano reports that the deal has no provision for a buyback clause and that the formalities of the deal should be concluded next week.
Dortmund have confirmed this week the signing of Thomas Meunier on a free transfer from Paris Saint-Germain, with the Belgian the natural successor for the Moroccan.
Matteo Guendouzi chased by European giants ahead of Arsenal departure - Euro Papers
Since the arrival of Antonio Conte, Inter have spent big in a bid to reclaim their place at the top of Italian football, having not won Serie A since 2010.
Romelu Lukaku was signed for a fee of €65 million last summer, and several other signings amount to almost an additional €100 million of spending.