Both drivers made gains on their qualifying efforts, Brown earning both pole, and a two-place yield, with a 1m13.954s.
That time was good enough to just edge big improver Reynolds, and prove too fast for provisional pole winner Cam Waters to run down.
"It was awesome," said Brown, now a four-time Supercars polesitter.
"I was watching everyone before and the times were a bit off and it was pretty hairy, so I thought, 'don't spray it at [turn 2]'.
"I probably braked a bit early. But I didn't make any mistakes and just put a tidy lap together. I thought there might be better than a 13.9s in it, but that's what got it."
Reynolds will start the race from the outside of the front row after improving a total of six positions with an impressive 1m13.995s.
Waters went backwards with the third-fastest Shootout time, while Shane van Gisbergen made up five spots to end up fourth on the grid.
Jack Le Brocq cost himself a shot at pole by out-braking himself into turn 2, but was able to recover to still take fifth on the grid, just a single-spot loss compared to qualifying.
Broc Feeney ended up sixth while Matt Payne lost five spots compared to his sensational qualifying effort and will start seventh.
James Golding will start from eighth with Ford pair Will Davison and Chaz Mostert locking out the fifth row.
The first 250-kilometre race of the weekend kicks off at 2:40pm local time.
Townsville 500 Top 10 Shootout results
| Cla | # | Driver | Car | Time | Gap |
|---|---|---|---|---|---|
| 1 | 9 |  Will Brown |
Chevrolet | 1'13.9454 | |
| 2 | 26 | David Reynolds |
Ford Mustang GT | 1'13.9955 | 0.0501 |
| 3 | 6 | Cameron Waters |
Ford Mustang GT | 1'14.0080 | 0.0626 |
| 4 | 97 |  Shane van Gisbergen |
Chevrolet | 1'14.0825 | 0.1371 |
| 5 | 34 | Jack Le Brocq |
Chevrolet | 1'14.1423 | 0.1969 |
| 6 | 88 | Broc Feeney | Chevrolet | 1'14.2373 | 0.2919 |
| 7 | 19 | Matthew Payne | Ford Mustang GT | 1'14.2462 | 0.3008 |
| 8 | 31 | James Golding |
Chevrolet | 1'14.5025 | 0.5571 |
| 9 | 17 | Will Davison |
Ford Mustang GT | 1'14.7700 | 0.8246 |
| 10 | 25 | Chaz Mostert |
Ford Mustang GT | 1'14.8374 | 0.8920 |
| View full results | |||||
