The 35-year-old and his family will leave their Sydney hotel quarantine on Thursday night, just before the Roosters take on Melbourne Storm at the SCG.
After completing a medical examination he will have his first training session with the Roosters at the weekend.
He has been using gym equipment while in the two weeks quarantine and although he's had minor knee surgery, is expected to hit the ground running after his recent stint with Toronto in the Super League.
Williams last played in the NRL in 2014, in between stretches in rugby union where he earned 58 caps for the All Blacks and won a World Cup.
Despite his achievements, Robinson sensed Williams would rise to the challenge of playing in the NRL again and play a role in their charge to a third successive title.
"We can talk about all his attributes and people can see them, it's the courage he has to play footy ... that's the biggest one," Robinson said of Williams.
"Around all the talents you see, the man has got a fire in him, he's got a hunger to perform and he loves playing in a team environment."
Williams is pencilled in to make his return in their round 17 grand final rematch against the Raiders in Canberra on September 5.
Robinson played his cards close to his chest when asked about how he planned to use the veteran.
"I'd like to keep those private, the conversations between Sonny and I about the way we'll use him," Robinson said.
"We've had lots of discussions and then we'll start to see him move and how he connects with the guys around him and that will give us a further idea about how we will use him."
