Williams is completing quarantine in Sydney before joining the Roosters, an opportunity that arose after the coronavirus pandemic forced his Toronto Wolfpack to quit England’s Super League.
The globe-trotting athlete, who has won two Rugby World Cups with the All Blacks and two NRL premierships in Australia duing 16 seasons of elite sport, acknowledged his career was winding down.
Auckland-born Williams said he planned to settle in Sydney long-term with his wife and four children.
“I consider Australia a home even probably more so than New Zealand as far as raising the kids and whatnot,” he said.
“I’m a realist. I’m 35, I’m not a spring chicken any more. I reckon I’ve got maybe one more year max in me.”
A devout Muslim with a proud Samoan heritage, Williams has previously said he wants to become involved in charity and helping minorities when his sporting career ends.
Williams played 58 times for the All Blacks, winning World Cups in 2011 and 2015, as well as numerous Bledisloe Cups and Rugby Championships.
Other honours include a Super Rugby title in 2012 and NRL premierships in 2004 and 2013.
He also represented New Zealand in rugby sevens at the 2016 Olympics and triumphed in all seven of his professional heavyweight boxing bouts, winning the New Zealand title in 2012.