Willison's partner gave birth last week and he missed Saturday's 22-12 loss to Cronulla, in which Brisbane's bench offered no punch.
Coach Kevin Walters axed prop Fletcher Baker and brought back Willison as a matter of priority for Friday night's showdown at Accor Stadium in Sydney.
Willison averages 35 minutes per match this season through nine games and has made them count.
He makes an average of 109 metres and two tackle breaks per match, as well as 20 tackles.
He is also two metres tall and has a tough streak to his game.
The Broncos are eighth on the ladder and not in dire straits, but they have lost their last two matches.
State of Origin will drain key forwards Pat Carrigan and Payne Haas, and they need a lift from the rest of the pack.
They did not get it against the Sharks, but Willison has shown he can provide some added thrust.
"Xavier makes an impact when he comes on," bench hooker Tyson Smoothy said.
Tyson Smoothy (centre) says the Broncos will be looking for their bench to have a huge impact. (Jono Searle/AAP PHOTOS)
"He has been massive for us this year, he is going to make a big difference for us with his carries.
"Xavier is so young. He has only played a handful of games and is only going to get better as he goes on."
The best sides in the competition have benches that make a difference.
The Sharks got a positive injection from Royce Hunt, Thomas Hazelton and Jack Williams last week.
The Broncos need it from Willison, Smoothy, Jack Gosiewski and Kobe Hetherington against a Rabbitohs side that has scored 88 points in two successive wins.
"Our bench had a solid game (against Cronulla), but all round we were disappointed in the result," Smoothy said.
"That is our role, to come on and make a difference.
"We are always looking to be better as a bench. We have a big game on our hands this week.
"Latrell (Mitchell) is a great player and we are going to have to look out for him."
The Broncos led 12-4 at halftime against the Sharks but collapsed after the break.
"We switched off and the Sharks caught us sleeping. We have to have the mindset to start the second half like the first half," Smoothy said.
"It was a disappointing result, but there were plenty of positives - we had a pretty solid first half.
"If we can do that for 80 minutes we will get the result. We are looking to bounce back."
