The Knights, whose star players Fletcher Sharpe and Kalyn Ponga both stood up, are now in sixth position on 28 points and with a bye still to come they need just one more win to play NRL finals.
It is a remarkable turnaround under new coach Justin Holbrook after claiming the wooden spoon last year.
The bumbling Broncos are in freefall after their 10th loss in 11 matches. Their premiership defence is over.
"It is tough because I have a high regard for how these boys go about things," coach Michael Maguire said.
"The boys are trying but things aren't going our way at the moment."
Brisbane have now lost seven straight games in Queensland for the first time in their history in the same season and six in a row at their spiritual home, Suncorp Stadium, their equal worst run at the venue.
The Knights led 10-0 after eight minutes, following a disastrous sequence of events for the hosts.
The Broncos had a horror start with second-rower Xavier Willison limping off in the sixth minute with a leg gash and captain Adam Reynolds following him with a concussion, which also ruled him out of the match and next week's 'Battle of Brisbane' with the Dolphins.
Winger Deine Mariner was sent to the sin-bin for a professional foul in the seventh minute.
The Knights had a dream start. Five-eighth Sharpe sliced through Reynolds with skill and pace to score. Ponga set up giant winger Dominic Young and it was 10-0 after eight minutes.
Half Sandon Smith, replacing injured Dylan Brown, was immense and the return of Ponga from injury was just the tonic.
"We have come off a few weeks of competing hard and just falling short so to come up here and have that performance I am thrilled," Holbrook said.
"I thought Sandon was outstanding and I am really happy with how the spine combined. It was great to have KP back."
Young and fellow winger Greg Marzhew, who scored a double, were unstoppable and caused the Broncos a world of hurt.
Reece Walsh was sin-binned for pulling the hair of Young and Newcastle second-rower Jermaine McEwen was marched at the same time for running in to get involved in a fracas.
The Knights have several boom forwards coming through and none more impressive than back-rower Francis Manuleleua, who threw a spiral 20m pass for Marzhew to score.
Newcastle extended their 14-0 halftime lead when Ponga handled twice in a scintillating backline move that was finished by hooker Phoenix Crossland.
Broncos talisman Walsh started and finished a razzle dazzle move to score under the posts. His conversion was bizarrely ruled a miss by both touch judges but the Bunker saved the day and correctly awarded it.
Brisbane's error rate was a disgrace and they only looked likely to score when Walsh got involved.
Sharpe's long-range coup de grace at the end of the match secured him a deserved second try.
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