Fornaro will maintain his position until the end of January 2020, when he will be replaced by current SVP and Chief Accounting Officer, Timothy Rishton, on an interim basis.
IGT's board unanimously approved Rishton to replace Fornaro as interim CFO while the operator searches for a permanent replacement.
Fornaro said: "It has been a great honour to serve as IGT CFO and to participate in the company’s success during the last eight years.
"With the recent completion of important refinancing activity and a strong finance organisation in place, it is the right time for me to move on to a new challenge."
Marco Sala, IGT CEO, said: "I would like to thank Alberto, both personally and on behalf of the IGT Board of Directors, for his leadership and outstanding contribution during the last eight years as CFO of first GTech and later IGT.
"Alberto played a significant role in improving our financial and operational performance, including helping to secure large, strategically important contracts for the next several years."
IGT generated revenue of $1.15bn for Q3 2019, a 3% rise year-on-year at constant currency.
