The 21-year-old was scouted by Broncos recruitment chief Simon Scanlan on a trip to Rotorua while he was playing for Wai-Coa-Bay Stallions.
Willison, then 15, had as his idol dual-international Sonny Bill Williams like so many New Zealand-born lads.
"It's actually a pretty crazy story," Willison said of his discovery, after starring in the 28-14 win over the Dolphins.
"I was playing union and I'd never even played rugby league, because rugby league's not really big in New Zealand, and my mate asked me if I wanted to come.
"They needed numbers for a rugby league team and then I got picked up from there by Simon Scanlan at the Broncos.
"Growing up, I wanted to be an All Black. That was my dream.
"Sonny Bill was probably my idol for his defence, his hits and his offloads."
Sonny Bill Williams charges into the Wallabies' defence during a 2017 Bledisloe Cup match. (Dan Peled/AAP PHOTOS)
Fast forward six years and Willison, who has played 14 games off the bench, has a different aspiration.
"My goal is to start for the Broncos and win a premiership," he said.
Willison, who spent his early years in Australia with the Broncos Academy, impressed Scanlan on first viewing.
"Xavier was a tall, wiry kid who didn't understand the game too much but he displayed great effort. I met him there in New Zealand, invited him over and signed him," Scanlan told AAP.
"He moved over and went to Palm Beach Currumbin High and played his footy at Burleigh while living with (prop) Ali Brown initially. Ever since he has displayed a very good work ethic. He is open to feedback and wants to get better.
"With a player like Xavier who hadn't played much league, the most important thing for us is to get them into a good system with the right coaching to improve them. Xavier has benefited from that."
Willison is signed until the end of 2025 and the Broncos want him to stay and play the rest of his career at the club.
He's had his ups and downs, including a labrum tear last year which ruled him out of contention for the finals series, and ultimately the grand final.
"It was definitely tough. I definitely wanted to be there and sitting on the sideline injured, I was pretty upset," he said.
"I thought the boys did really well and hopefully we can get there again (to the grand final) this year."
Pat Carrigan (L) and Xavier Willison (R) during a Broncos training drill at Red Hill. (Darren England/AAP PHOTOS)
Willison, whose mother moved over from New Zealand a year after he joined Brisbane, still keeps in touch with Burleigh legend Brown and has found another quality mentor in Broncos forward Payne Haas.
"Payne has been a really good mentor," he said.
"He's teaching me as I go. I've still got a lot to learn and he's been really good … and Patty Carrigan actually.
"I am still learning the game and slowly getting better and hopefully I can get my minutes up."
If he can keep playing like he did against the Dolphins – where Willison ran for 181m, made 18 tackles and scored a barge over try – he will get his wish.
Willison will have another stern test of his development on Saturday night against Canberra at Suncorp Stadium.
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