The defending premiers gave up a 20-6 lead and it was Eels' five-eighth Pezet who sealed it with a 79th minute try after setting up an incredible four tries at Suncorp Stadium on Thursday night.
The Broncos' woes were compounded by captain Adam Reynolds leaving the field in the 76th minute with a rib injury.
It was a crazy match where tries came in waves. Players from both sides made unfathomable mistakes and conjured acts of genius
A freakish chip-and-chase by Reece Walsh in the second half to regain the lead for the Broncos was one of them, but it wasn't the decisive play.
That fell to Pezet, whose last try assist was a crafty grubber that was brilliantly gathered and plonked over the line by Sean Russell for a 34-32 lead.
Pezet then sealed it with a grubber and regather of his own. The 23-year-old will become retirement-bound Reynolds' successor in 2027 and a worthy one he will be.
"That is our footy club. You play for Parramatta and you fight for every play and contest," a proud Eels coach Jason Ryles said of the comeback win..
"We've seen that in live action."
Ryles said Pezet's display was "really pleasing" but didn't pump up his tyres too much.
"He is a work in progress and there are areas of his game we want to keep working hard on," he said.
The Broncos led 20-6 in the 31st minute and appeared in control but the Eels scored three tries inside five minutes to take a 22-20 lead into halftime.
Pezet laid on two first-half tries. The first came with a grubber kick that was fumbled by Payne Haas and swooped upon by Ryley Smith.
The second was courtesy of a sublime Pezet short ball for rampaging second-rower Kelma Tuilagi to score his second try.
It got better for the Eels when Isaiah Iongi sliced through as Brisbane's left edge defence fell apart with Ezra Mam and Gehamat Shibasaki failing to communicate.
"We were up by 20 points and then we softened and teams find you out," Broncos coach Michael Maguire said.
"We had a few issues on the left. We need to be better. We're not hitting the mark."
Walsh dropped a sitter after the break and Iongi ran a super line soon after to extend the visitors' lead.
Mam made amends with a subtle dink of a kick behind the line for Kotoni Staggs to notch his 15th career try double. Defence had become an optional extra at 26-all in the 48th minute.
Reynolds started the game with a real spring in his step with his kicking and passing games on song. The 35-year-old also wound back the clock with two line breaks.
Tries to Walsh, Staggs and Haas early appeared to have the Broncos on track for a big win but Pezet's Eels had other ideas.
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