Brook’s effort, which included four fours and four sixes, underpinned his partnership of 90 from 46 with skipper David Willey as the Vikings fought back after a dreadful start to post 190 for seven at Wantage Road.
Yorkshire all-rounder Matthew Waite registered a T20 career-best with both bat and ball, following an unbeaten 35 from 20 with figures of three for 18 as the home side crumpled to 128 all out in 16.2 overs.
It was a third straight defeat for the Steelbacks – the space of just four days – and they now face a struggle to make the quarter-finals.
Josh Cobb’s decision to send Yorkshire in after winning the toss was swiftly justified as the Steelbacks skipper (one for 16) opened proceedings with two tight overs and the wicket of Fabian Allen, caught off a leading edge at short cover.
With Adam Lyth and Tom Kohler-Cadmore both holing out to Ben Sanderson, the visitors slumped to a perilous 11 for three in the fourth over before Willey (31 from 24) and Brook hauled them back into the game.
Willey, who rejoins Northants at the end of the season, was required to play little more than a supporting role while his partner tore into the bowling, lifting Sanderson, Tom Taylor and Jimmy Neesham for a series of majestic leg-side sixes.
Aside from a powerful drive straight back at Sanderson, who could only parry the ball, Brook offered no chances as he raced to his half-century from 21 deliveries and looked odds-on to convert that into a ton.
However, he became one of three victims in five balls for Graeme White (three for 30) – and the only controversial one of those dismissals, given out caught behind after swinging across at the left-arm spinner.
Any prospect of a renewed Vikings collapse was averted by Jordan Thompson (30) and Waite, who crashed Sanderson for three boundaries off the final over as the visitors finished with a flourish.
Steelbacks made just as subdued a start to their innings, with Ben Curran chopping on to Willey and Shadab Khan’s tidy leg-spin provoking Cobb into a wild heave that saw his bat fly towards square leg, while the ball sailed away into the hands of backward point.
But it was Waite who collected the prize scalp with his third delivery as big-hitting opener Chris Lynn speared it straight to Willey at mid-on to leave the Steelbacks teetering at 22 for three.
Neesham briefly revived his side’s hopes by hammering 26 from 13 but, having dispatched Shadab over the midwicket fence twice in an over, he picked out the point fielder next ball – and the procession gathered pace.
Dom Bess (two for 25) struck twice in as many deliveries and, despite a late flurry of boundaries by Nathan Buck (19 from 11), the outcome was never in doubt.