The Robins deserved their victory and the title of the planet's greatest club rugby league side after dominating for the majority of the clash at Hull's MKM Stadium.
It was a triumph for the ages for Robins coach Willie Peters whose team had been written off before the match by pundits in Australia.
Peters and his team have now won the quadruple - the Super League major and minor premiership, the Challenge Cup title and the World Club Challenge.
It was five tries each with Broncos captain Adam Reynolds landing just two from five attempts, his last two misses proving crucial.
The Robins led 30-4 in the 57th minute after Peta Hiku followed a Tyrone May grubber.
The Broncos, famous for their three comeback wins in the finals series last year to win the NRL title, clicked into gear.
"It was the longest 20-odd minutes of my life," a delighted Peters said.
"I am just really happy with the way they scrambled, fought and dug in to win.
"We were the underdogs. Not many people thought we could win."
Broncos coach Michael Maguire rued his side's penchant for playing catch-up footy.
"We didn't go with them at the start," he said.
"Unfortunately if you are going to wait until the end of the game over and over eventually it is going to hurt you. It is something we need to sort out."
Bench prop Ben Talty burst through to put Pat Carrigan over and a minute later winger Deine Mariner streaked down the right touchline as the comeback began..
Reece Walsh threw a corker to put centre Gehamat Shibasaki over and the Broncos had three tries in five minutes.
Robins five-eighth Mikey Lewis failed to find touch from a penalty at the death and the Broncos went the length through Kotoni Staggs to set up a thrilling final three minutes.
Hull KR forwards Sauaso Sue and Dean Hadley were dominant. The Robins completed 19 of 21 sets in the first half with the kicking of Lewis integral.
Broncos prop Corey Jensen was concussed inside 90 seconds after what appeared to be friendly fire from teammate Payne Haas.
The hosts dominated early and raced to an 18-0 lead after 23 minutes.
Half May put in an ugly old kick that dribbled along the ground for desperate prop Tom Amone to score.
Walsh then spilled a bomb, much to the crowd's delight.
Hull KR skipper Elliot Minchella crashed between tepid defence from Cory Paix and Walsh to extend the lead.
The kicking game of the hosts was sensational and a deft effort by hooker and man-of-the-match Jez Litten was swooped on by winger Joe Burgess and the Robins were up by three converted tries.
The Broncos got one back due to Walsh magic with a cross-field kick and slick reaction from winger Josiah Karapani to get the ball back inside for Gehamat Shibasaki to score.
Hull KR showed they would not back down for reputations. Minchella elbowed Broncos winger Deine Mariner in the head early and Walsh came rushing in.
The hosts lost dazzling fullback Arthur Mourgue just before halftime with a suspected pectoral injury, forcing Lewis to switch to fullback.
The hype around the Broncos before the match was misplaced considering English clubs led 15-14 in the history of World Club Challenge contests leading into the contest.
The Robins extended their lead to 26 points after the break and hung on.
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