The 35-year-old forward, who won Rugby (Union) World Cups with New Zealand in 2011 and 2015 and was in the Kiwis team who reached the 2013 Rugby League World Cup final at Old Trafford, made the announcement on Twitter.
Williams tweeted: “A massive thank you to the public and fans for all the support over years.
“To my many team-mates, thanks for the lessons and help along the way. It wasn’t a perfect journey, but the lessons have helped shape me into the man I’m proud to be off the field today.”
A massive thankyou to the public & fans for all the support over years. To my many teammates, thanks for the lessons & help along the way. It wasn’t a perfect journey,
but the lessons have helped shape me into the man I’m proud to be off the field today. #AlwaysAlhamdullilah 🤲🏽❤️ pic.twitter.com/aECnrTYCJs
— Sonny Bill Williams (@SonnyBWilliams) March 11, 2021
Williams’ last appearance was for Sydney Roosters last October as part of a short-term stint following Toronto Wolfpack’s withdrawal from their first season in Super League.
He was still under contract for 2021 but was left without a club when the Canadian outfit failed to gain re-admission in to Super League.
It marked a low-key finale to one of the greatest careers of the modern era in either code of rugby.
One of 33 men to have represented New Zealand in both codes of rugby, he won 58 caps for the All Blacks and a Super Rugby title with the Chiefs in 2012 and also represented New Zealand at the 2016 Olympics in Rio de Janeiro.
In league, he won two NRL premierships across his 123 games at the Roosters (2013) and Canterbury Bulldogs (2004) and was a major capture for Toronto, who are thought to have splashed out around £5million to tempt him back to the 13-man game in November 2019.
Williams won all seven of his professional heavyweight boxing bouts and is now set to focus on reviving that aspect of his career, although he has also been offered a mentoring role by the Roosters.
— Sydney Roosters 🐓 (@sydneyroosters) March 11, 2021