Newcastle backed up after a four-day turnaround to beat Brisbane 28-20 and momentarily move into the NRL's top eight.
The return of halfback Mitchell Pearce inspired the Knights to an eight-point victory at Suncorp Stadium that has kept their finals hopes alive for another week.
Injuries have kept the star No. 7 to just seven games in 2021 and Thursday night's was just his second game of the season with fullback Kalyn Ponga.
The 32-year-old scored a try of his own, but both playmakers created points around them for the win just four days after they beat Canberra.
With four weeks left in the season, the Knights are in a fight for a top-eight finish along with four other teams, including Cronulla, who they face next in round 22.
They'll need wins against Canberra, Gold Coast and then the Broncos again in the final round of the season to ensure their spot.
But if their start on Thursday night was anything to go by, the Knights are up for the fight.
For the first eight minutes, the Knights kept possession of the ball by forcing the Broncos into errors on their goal line.
Despite the seven straight sets, the Broncos held strong until given a sniff of an opportunity at the other end.
In their first venture into Knights territory fullback Tesi Niu scored, running the ball on the last to put the Broncos up 4-0.
But key for the Knights was not losing momentum after the setback, and the defence manned up to drive Payne Haas into touch on the kick return.
Soon they struck back through Jake Clifford to take the lead as tries were exchanged to round off a 12-8 lead for the Knights at the break.
Tyson Frizell busted through soft middle defence to run 50 metres and set up the first try of the second half, with Barnett and Enari Tuala extending the Knights' lead to 28-8.
They survived a late scare as the Broncos ran in two tries in six minutes to Xavier Willison and Herbie Farnworth with seven to play.
Farnworth and Niu showed the most promise for the Broncos, who will now face Sydney Roosters on Friday night.
Meanwhile, there was concern for Hymel Hunt after he took a heavy knock in the first half and failed his HIA.
The Knights winger copped Keenan Palasia's shoulder to the chin and looked in a worrying state on the turf after the hit.
Palasia was penalised for the shot, which could come under scrutiny from the NRL's match review committee on Friday morning.