A combination of speed and smart strategy allowed Feeney to leap-frog the Tickford Racing Mustangs of Cam Waters and Thomas Randle, which had locked out the front-row.
Brown meanwhile rose from fifth on the grid to move into third with just over 20 laps to run – the exact spot he needed to put the championship beyond doubt.
The 26-year-old then completed Triple Eight’s storybook day by overtaking Waters 10 laps from home to score a team 1-2.
The 78-lap race was run in hot but overcast conditions, adding to Brown’s feeling of relief at the finish.
“I think I was more glad it finished because it was so hot out there,” he said when asked of securing the title.
“I wish I could go out and get on the beers tonight but I can’t, I’ve got to behave, that’s tomorrow night.
“Just stoked to wrap it up today, it’s awesome. Bit of pressure off, I’ll go out tomorrow and have some fun.”
Thomas Randle beat pole-sitter Waters off the start as the Tickford duo led Matt Payne, Feeney and Brown, who went side-by-side with Aaron Love through much of the opening lap.
Feeney took third from Payne on lap four in a clean Turn 6 pass that also opened the door for Brown to demote the Grove Mustang to fifth.
Randle showed the way throughout the first stint, leading by as much as 2s over Waters, who ensured the gap was half that by the time the leaders began to pit.
The top five were separated by less than five seconds when Triple Eight pulled the trigger on Feeney’s first pit stop 26 laps in.
Randle and Brown were both in on the next lap before Waters and Payne completed the successive stops on lap 28.
A short fuel-fill for Feeney meant he now led from Randle, Waters, Payne and Brown – Triple Eight effectively throwing down the challenge to Tickford by taking track position.
The strategic puzzle appeared to be thrown a curveball when Dale Wood – subbing for Richie Stanaway at Grove Racing – parked the #26 Mustang in the gravel at Turn 5 on lap 41.
However, the Carrera Cup ace was able to reverse his way out of trouble without a Safety Car being required.
Tickford soon had an internal challenge on its hands as Waters closed in on Randle. Waters spent several laps behind the Castrol entry before Randle moved over on lap 46.
The next round of stops kicked off with Randle and Waters pitting on laps 50 and 51 respectively.
Feeney’s pace was such that he pitted on lap 52, took on his larger second fuel load and rejoined narrowly ahead of Waters.
Brown and Payne ducked in for their final stops on lap 53, leaving the order as Feeney, Waters, Randle, Brown and Payne for the 25-lap run to the flag.
Brown made his move on Randle at the Turn 9 hairpin on lap 57, before shifting his eyes forward to the six-second gap up to Waters.
Randle meanwhile fell into the clutches of Payne, who demoted the Castrol Mustang to fifth on lap 60.
Brown’s pace was such that he also caught Waters and, seemingly unsatisfied with cruising to the title, pulled a Turn 6 pass on the Monster Mustang for second on lap 67.
Waters was left to fend off Payne for the final spot on the podium, taking the flag narrowly ahead of the Penrite Mustang, while Randle came home fifth.
Erebus Motorsport’s Brodie Kostecki was the best-of-the-rest, leading the race by running long on his first two stints on the way to sixth place.
Seventh through 10th were filled by Andre Heimgartner, James Courtney, Anton De Pasquale and Ryan Wood.
The two ‘supersubs’ endured difficult days.
Cooper Murray, driving Jack Le Brocq’s Erebus Camaro, was out of contention early as front-end damage forced him to the garage.
He later earned a penalty for a tangle with Mark Winterbottom and, among other dramas, finished 24th, two places behind Dale Wood, who had started from pitlane in the Stanaway Ford.
Between them was David Reynolds, whose Team 18 Camaro required a stint in the garage after contact caused a mechanical failure.
The Supercars field will return to the track on Sunday for qualifying, a Top 10 Shootout and the 250km season finale.
Results: Repco Supercars Championship VAILO Adelaide 500, Race 23
Pos | Num | Driver/s | Team/Sponsor | Car |
1 | 88 | Broc Feeney | Red Bull Ampol Racing | Chev Camaro ZL1 |
2 | 87 | Will Brown | Red Bull Ampol Racing | Chev Camaro ZL1 |
3 | 6 | Cam Waters | Monster Castrol Racing | Ford Mustang GT |
4 | 19 | Matthew Payne | Penrite Racing | Ford Mustang GT |
5 | 55 | Thomas Randle | Monster Castrol Racing | Ford Mustang GT |
6 | 1 | Brodie Kostecki | Erebus Motorsport | Chev Camaro ZL1 |
7 | 8 | Andre Heimgartner | R&J Batteries Racing | Chev Camaro ZL1 |
8 | 7 | James Courtney | Snowy River Racing | Ford Mustang GT |
9 | 11 | Anton De Pasquale | Shell V-Power Racing | Ford Mustang GT |
10 | 2 | Ryan Wood | Mobil1 Truck Assist Racing | Ford Mustang GT |
11 | 14 | Bryce Fullwood | Middy’s Racing | Chev Camaro ZL1 |
12 | 17 | Will Davison | Shell V-Power Racing | Ford Mustang GT |
13 | 25 | Chaz Mostert | Mobil1 Optus Racing | Ford Mustang GT |
14 | 10 | Nick Percat | Bendix Racing | Chev Camaro ZL1 |
15 | 31 | James Golding | PremiAir Nulon Racing | Chev Camaro ZL1 |
16 | 96 | Macauley Jones | Pizza Hut Racing | Chev Camaro ZL1 |
17 | 18 | Mark Winterbottom | DEWALT Racing | Chev Camaro ZL1 |
18 | 4 | Cameron Hill | SP Tools Racing | Chev Camaro ZL1 |
19 | 50 | Jaxon Evans | SCT Motorsport | Chev Camaro ZL1 |
20 | 23 | Tim Slade | PremiAir Nulon Racing | Chev Camaro ZL1 |
21 | 3 | Aaron Love | REDARC Racing | Ford Mustang GT |
22 | 26 | Dale Wood | Penrite Racing | Ford Mustang GT |
23 | 20 | David Reynolds | Tradie Beer Racing | Chev Camaro ZL1 |
24 | 9 | Cooper Murray | Erebus Motorsport | Chev Camaro ZL1 |