But the Sydney-based Whittaker was able to absorb the flurry as he kept himself in the bout.
Whittaker showed his near-flawless takedown defence as Brunson (16-4) also looked to use his high-level wrestling before a left hook counter-punch from Whittaker changed the complexion of the fight.
With Brunson on wobbly legs, Whittaker continued to pepper the American with accurate shots before a head kick left Brunson out on his feet.
From there, Whittaker swarmed with a barrage of punches and with four minutes and seven seconds gone in the first frame, referee Herb Dean stopped the fight as the crowd at Rod Laver Arena exploded.
"We had a solid gameplan," Whittaker said after the fight. "We knew he was going to come out tough but I had no idea he was going to come out that hard.
"He hits hard. Very hard."
Whittaker entered the bout at No 7 in the middleweight rankings, with Brunson at No 8, and this win will put him in the frame to potentially be one victory away from a title shot.
The middleweight division is a talent-laden one that is ruled by brash Brit Michael Bisping (30-7), while fellow big names Luke Rockhold (15-3), Yoel Romero (13-1) and Ronaldo Souza (23-4, 1 NC) are also among the top dogs.
"I'm ready for the top-five contenders," Whittaker declared.
With his second son due next month, Whittaker was given some extra reasons to smile as he won two US $50,000 post-fight bonuses. One for being involved in the 'Fight of the Night', while the other was a 'Performance of the Night' bonus for his impressive win.
Meanwhile, Dan Hooker is still searching for consecutive victories in the UFC.
The Kiwi featherweight dropped a unanimous decision to Jason Knight (15-2) on today's undercard.
Hooker, who made his UFC debut in his hometown of Auckland in 2014, has alternated three wins and as many losses during his time with the promotion.
After submitting Mark Eddiva (6-3) via guillotine choke at UFC Fight Night 85 in Brisbane in March, Hooker had the opportunity to record back-to-back wins in the UFC for the first time.
But Knight proved a tough opponent with his volume striking and solid wrestling setting up his victory. Hooker too often looked for one-out shots and didn't set up combinations to take advantage of his length.
The judges scored it 30-26, 30-27 and 29-28 all in favour of the American. The loss dropped Hooker to 13-7 in his MMA career.
"I came here to beat the next guy in my way," Knight said in the cage after the fight. "That's what I came here for. I hope I gained some fans."
Hooker will head back to the drawing board for 2017 as he plots his next move, while 2017 promises to be a huge year for Whittaker.
