Sonny Bill Williams to fight Bachelorette winner

Sonny Bill Williams will fight Australian millionaire pub owner Stu Laundy in what should be a gentle return to the boxing ring.

In an announcement which confirms the charitable nature of the fight, All Blacks star Williams will trade blows with 44-year-old Laundy, a prominent reality TV celebrity.

It is the headline event of the "Banger under the Hanger" promotion in Sydney on December 1.

Williams, 33, boasts a 7-0 professional record and is a former New Zealand heavyweight champion. His last fight was nearly four years ago.

"I'm looking forward to getting back in the ring again. I know this will be a hard fight for me," Williams said.

"Some people will say I'll be rusty. But I can't wait! I know I'll put on a good show and the cause is a great one. It feels good to be giving something back."

Sophie Monk chose Stu Laundy to win the Bachelorette. Pic: Getty

The fight falls on the weekend after the All Blacks' final Test of the year, against Italy in Rome.

New Zealand coach Steve Hansen has received assurances from Williams and his agent Khoder Nasser that Williams won't be compromised, with rugby taking priority over boxing training throughout a five-week tour of Japan and Europe.

Father-of-two Williams has battled wrist, knee and shoulder injuries this season.

His lone Test appearance came against France three months ago before limping off injured in the second half. He hasn't played since.

Sonny Bill Williams has fit boxing in around his rugby career. Pic: Getty