Super League chief executive Robert Elstone says an agreement has been reached with Betfred - one of the UK's biggest betting companies. Gambling is considered 'haram' or forbidden in Islam, along with other practices like drinking alcohol.
Williams converted from Christianity to Islam in 2009 and was the first Muslim to play for the All Blacks.
"I think the matter has been resolved in satisfactory fashion," said Elstone. "I have say a big 'thank you' to Betfred for the way they've managed this.