The club released a statement on Monday afternoon confirming his decision, with the defender’s preference being a move to a Victorian club.
The 26-year old wants to be closer to his sister who lives in based in Albury.
“It’s disappointing to receive this news as Zac has come a long way since coming through the Giants Academy pathway,” Giants General Manager Football Jason McCartney said told the club website.
“We understand that free agency is part of the current football landscape and that the players have the right to go down this path.”
Williams has played 113 games for GWS after getting drafted with Pick 95 in the 2013 AFL Draft.
He averaged 16.9 disposals from 11 games this season.