The 16-year-old Young Socceroo will not officially join the club - currently home to fellow Australian Kwame Yeboah - until he turns 18 - on July 30 2019.
In the meantime, he will continue his football education with Glory, with Gladbach to make a down payment on the rookie and several further installments over the next 17 months.
Gladbach, sixth on the Bundesliga after 17 rounds, have developed an eye for Australian talent, with Mathew Leckie beginning his booming career in Germany there after signing from Adelaide United in 2011.
In 2014, Yeboah followed suit when he signed for Gladbach from Brisbane Roar.
Attecking weapon Italiano is likely to be groomed in Gladbach's second team, which plays in the fourth tier of German football, when he ultimately departs Perth.
In the short-term, he will miss Thursday's A-League clash against Brisbane Roar at Suncorp Stadium as he, and his agent John Grimaud, iron out the finer details of the deal.
Grimaud, who also took Leckie and Yeboah to the North Rhine, may have other business to conclude while in Germany with Yeboah possibly looking at a January loan move to the 2.Bundesliga.
Despite brimming with promise, the 23-year-old has yet to convince head coach Dieter Hecking he is worthy of a senior call-up, and is desperate for first team football to elevate his prospects of being selected for the Socceroos at next year's World Cup.