The 35-31 win featured a stunning display by Cowboys fullback Scott Drinkwater.
Brisbane young gun halfback Tom Duffy had a brilliant club debut against his former team.
Duffy, 22, landed a 75th-minute field goal with ice in his veins for the hosts to take a 31-30 lead. Drinkwater responded with his own one-pointer two minutes later, before Luki dived over out wide with two minutes left.
Duffy filled in for injured captain Adam Reynolds with aplomb to set up two tries and lay on three linebreak assists in front of 45,582 fans at Suncorp Stadium.
The Broncos lost two hookers - Cory Paix and Blake Mozer - to concussion in the second half, while lock Pat Carrigan was put on report.
Mozer was playing his first NRL match in 18 months but took a fierce blow to his jaw tackling Cowboys giant Jason Taumalolo.
The Broncos were without injured star trio Reece Walsh, Reynolds and Ben Hunt.
The first half was dominated by the creative genius of Drinkwater and the speed of centre Jaxon Purdue.
Drinkwater has been given permission to negotiate a deal elsewhere for the final year of his contract in 2027.
Purdue, who inked a $3 million four-year extension on Tuesday, is ironically the man likely to replace Drinkwater at fullback.
The visitors dominated the first half with 71 per cent of the territory but only led 24-18 after the Broncos struck three times, largely against the run of play. The hosts also scrambled well to restrict the damage.
Duffy had a great start to the match, with a nifty short grubber kick setting up centre Kotoni Staggs for the opening try.
Purdue lit up the stadium with a 75m run that included a change of direction and acceleration that left Duffy and Broncos fullback Jesse Arthars in his wake.
Drinkwater, who had set up the Purdu try, laid on another for Zac Laybutt and the visitors led 12-6.
Both tries were scored with Broncos captain Pat Carrigan in the sin bin for a shoulder to the head of Cowboys centre Tom Chester.
Cowboys bench hooker Soni Luke, who replaced concussed starting No.9 Reed Mahoney, danced over from dummy-half..
Broncos five-eighth Ezra Mam struck a blow when his cutout pass sent winger Josiah Karapani over.
Drinkwater pulled in a Luki pass one-handed and at speed in another stunning display of skill to score as Mam and centre Gehamat Shibasaki struggled on the left edge in defence.
Lock forward Carrigan found a pass for the ages to put a flying Arthars over 40 seconds before halftime, and somehow the Broncos trailed by only six.
After the break a stellar cutout pass by Duffy set Karapani clear and his in-field kick was brilliantly grounded by Mam and it was 24-24.
Brisbane prop Ben Talty stormed in off a Duffy pass but Chester, who was phenomenal for the Cowboys, levelled at 30-30 to set up a grandstand finish.
Veteran Cowboys lock Taumalolo and Broncos prop Payne Haas were both enormous.