Recalled winger Selwyn Cobbo was brilliant and fullback Reece Walsh had four try assists and a try in a powerful riposte to his poor display against Parramatta the previous week.
The Rabbitohs remain in last place and their ninth loss in a row is now Wayne Bennett's worst losing streak in his 38 years as coach in the premiership.
The loss of Willison in the 48th minute, likely for the season, is a concern for the Broncos in the run to the finals with fellow prop Ben Te Kura (broken foot) also out of action.
"He has broken his arm and that could be a six-weeker," coach Michael Maguire said of Willison.
"Watching 'X' grow has been great, but we have someone like Ben Talty to step up."
Maguire said before the match that he wanted Walsh to pick his moments and chime in at the right time rather than overplaying his hand.
Walsh took the advice on board to set up two tries in the first half as Brisbane took an 18-8 lead into the break.
"The players took a lot out of what we went through last week. They were thorough and I thought our spine was very good," Maguire said.
Bennett said he had never endured an injury toll like this year.
"I was waiting for that performance. We have been battling for a long time," he said.
"We were missing 13 players, but we competed with them for the first 25 minutes.
"I can't ask for more than that. We have given young guys some experience and that will hold us in good stead next year."
Cobbo had several nice touches and raced 53m to score straight after halftime. Fellow winger Deine Mariner, also brought back into the side, was at his dazzling best with a try double.
Ezra Mam and Kotoni Staggs both scored twice as the Broncos romped home.
Brisbane, on 28 points, are now just two points behind the fourth-placed Warriors and travel to Melbourne on Thursday night.
The hosts lost forwards Payne Haas (skin infection) and Brendan Piakura (concussion) in the 24 hours before kick-off but had too much class for the injury-ravaged Rabbitohs.Â
Maguire said star prop Haas "got a nick on his leg" at captain's run which turned into an infection.
"The docs put him on a drip and he was keen to play, but he will be OK for next week," the coach said.
Broncos captain Adam Reynolds became the second player in premiership history to score 2500 points and now is behind only Cameron Smith (2786 points).
Walsh and Mam interchanged passes in a slick long-range try for the latter to open the scoring.
Reynolds then conjured a trademark try for Jack Gosiewski with a deft grubber.
Rabbitohs five-eighth Lewis Dodd set up a try with a neat cross-field bomb for winger Bayleigh Bentley-Hape to score.
Walsh found the perfect pass for Staggs to surge over but Souths spun it as the halftime siren sounded for centre Tallis Duncan to score.
The hosts ran away with it in the second half in a total demolition.
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