Willison played 21 games in Brisbane's 2025 premiership season and appeared in every Broncos match in 2026, including the World Club Challenge.
He averaged 123.9 running metres per game, with 43 tackle busts, 11 offloads and four line breaks.
The New Zealand representative was named on the interchange bench for the Kiwis' World Cup opener against Australia.
The Australian reports that Willison has verbally agreed to a $4 million extension but will wait until November 1 to sign.
The delay would let agent Ahmad Merhi avoid obligations to Willison's former manager, Dixon McIver Management; Merhi also represents Payne Haas.
Brisbane's current offer spans three years, potentially four; July reports described a five-year, $3 million proposal.
That earlier offer would have made Willison the second-highest-paid Bronco, behind Reece Walsh.
September reports linked him to South Sydney if Brisbane could not re-sign him before November 1; the club is pursuing an extension after Haas joined the Rabbitohs in the pre-season.