The 25-year-old should now remain a Bronco until the end of the 2017 season. He has scored nine tries so far for the club in 2015.
“I’m pleased to sign the contract and get things out the way early so I can concentrate on the rugby,” said the winger.
“I think my form has been pretty good. To get on the score sheet as much as I have has been good.
“In terms of the team performances we’ve got a little way to go but we are getting things together and getting the wins but we need to be more consistent.
“As long as I’m playing well, I’m happy with my form, and contributing to the team, the tries will continue to come.
“For me it’s a bit of stability, over the last few years I’ve been in and out of teams and on loan. I wanted to be settled and focus on one team, which will really benefit me.
“To play in the same team week in and week out makes a big difference.”
Broncos coach Andrew Henderson was also happy that Williams was set for a longer stay at the club.
“I’m really pleased that Rhys has decided to stay with the club, he’s been fantastic and one of our form players this season,” he said.
“He’s someone that typifies what we are about, he’s genuine and honest. He’s a good person to have around the place and fits into my core values and ideals are for the club.
“Ultimately he’s performing on the pitch and I was more than happy to offer him a new deal.
“He’s a quality player that still has a lot more in him and he can give the club a lot more in the next two years.
“I just hope for his sake we can bounce back to Super League and can give him that opportunity to establish himself in the top league.”