Fuccillo has left his post as chief scout at Newcastle to take up the post at the Welsh club.
Fuccillo will replace Kevin Reeves, who followed former boss Roberto Martinez to Wigan earlier this summer.
Swans chairman Huw Jenkins told the club's official website: "We are absolutely delighted Lil has agreed to join us.
"His appointment is the missing link we've been trying to fill for the last few weeks.
"To secure the services of someone with Lil's knowledge, experience, contacts and network of scouts is a massive plus for the club."