After a maiden ODI century at Chester-le-Street on Tuesday, Brook appeared to be at the top of his game as he peeled off 87 from 58 balls at Lord's in a contest reduced to 39 overs a side because of rain.
The stand-in England captain's innings underpinned a mammoth total of 312 for five - requiring Australia to go at eight an over in reply and they duly subsided to a sorry 126 all out in 24.4 overs.
Coming back from 2-0 down at the start of the week to level at 2-2 to set up a winner-takes-all showdown this weekend was all the sweeter for Brook following his uptick in form.
The Yorkshireman averaged a respectable 37.7 in Tests this summer but he made one hundred and passed fifty only once in his last seven innings, while he was singled out for criticism in the defeat against Sri Lanka at the Kia Oval this month by former England captains Michael Vaughan and Sir Alastair Cook.
Any concerns are now in the background after back-to-back innings of substance, in which Brook injected some impetus after a tricky start and manoeuvred the field at will.
"It felt like only a matter of time for me," he said. "I feel like I've been playing well all summer, everything just needed to click. The last couple of games for me have been really special.
"It's definitely the best I've hit it this summer. That's how I feel like I play at my best and thankfully it came off."
Ben Duckett came through a probing opening spell from Mitchell Starc and Josh Hazlewood to contribute 63 off 62 deliveries before Liam Livingstone's jaw-dropping demonstration of six-hitting.
Livingstone belted seven in total, including four in Mitchell Starc's final over which yielded 28, to equal Andrew Flintoff's record for the most sixes in an ODI at Lord's.
His 25-ball fifty is the fastest in this format at the home of cricket and he finished on a swaggering 62 not out off 27 balls to leave Australia reeling, with only 20 minutes between the change of innings.
"He was striking it unbelievably well," Brook said. "We all know what he's capable of doing at the back end and he did it immensely well."
After Travis Head and Mitchell Marsh had put on 68 inside nine overs, Australia imploded with Brydon Carse and Jofra Archer in a pace race and exploiting helpful conditions under the floodlights.
They took five of the first six wickets to fall, Archer getting up to 93mph and Carse not too far behind, before Matthew Potts took four for 38 to hasten Australia's demise.
"It was phenomenal to watch," Brook said. "We knew the seamers were getting the most out the pitch so I just tried to bowl them as many overs as possible.
"Carse is a little bit ill so he was struggling with his chest but they all bowled unbelievably well. We've got an awesome bowling attack with those three seamers."
Momentum is firmly with England after winning the last two ODIs but their bid to finish their summer with a flourish could be spoiled by the weather in Bristol, with rain forecast.