The 19-year-old will move to the Italian club for an undisclosed fee, subject to international clearance.
McJannet has represented Republic of Ireland at Under 17, 18 and 19 levels, the latter of whom he has captained on a number of occasions.
The Town academy graduate was an unused substitute for the first-team in the FA Cup and EFL Cup last season and will now join up with the Italian club who are 15th in Serie A.
Best of luck for the future, Ed!