The win keeps the County to keep them firmly in the qualification mix from the North Group of the NatWest T20 Blast.
Levi and Rossington hammered 72 from the first five overs of Northants’ chase of 158, and the rest of the innings was a formality as victory came in the 18th over.
Northants climbed to second in the table while a fifth defeat for Worcestershire left them teetering on the brink of elimination.
After Richard Gleeson and Rory Kleinveldt shared six wickets to help bowl the visitors out for 158, Levi and Rossington produced a brutal display of hitting.
Most of the runs came down the ground with nine fours and four sixes in the opening five overs, giving Worcestershire similar treatment to that dished out to them by Derbyshire at New Road.
Pat Brown, the 18-year-old playing in just his second Worcestershire match, was taken for 26 in two overs.
Rossington, having driven Jack Shantry with particular gusto, made 42 in 20 balls before sweeping Joe Leach - the fifth bowler in seven overs - to long-on.
Levi, after knocks of 41 and 88 on return from concussion, was again in excellent touch and made 47 from 32 balls before chipping John Hastings straight to cover as Northants reached 100 for three a the halfway stage,
Ben Duckett also out caught and bowled for a three-ball duck.
But Northants captain Alex Wakely and Rob Keogh have both enjoyed good form in the competition and they ended any chance of the chase becoming tight with a half-century stand for the fourth wicket, Wakely heaving two sixes over midwicket in his 46 from 28 balls.
Earlier, Richard Gleeson produced a superb new ball spell after Northants had won the toss.
Having not previously taken a wicket in the competition this season he took three in two overs.
Joe Clarke never looked settled and stepped away to swing wildly and inside-edged into his stumps.
Ben Cox did the same looking to drive a very full ball just outside the off stump, and Hastings received a superb yorker first delivery.
Gleeson’s first three overs conceded only 10 runs and he finished by matching his career-best: four overs, three for 12.
It was an excellent powerplay for Northants as Worcestershire made only 35 for three but Mitchell Santner tried to inject some momentum into the innings with the night’s first six over long-on as Steven Crook’s first over went for 13.
Santner struck another six off Keogh over long-off but picked out the same fielder trying to pump a full-toss.
Santner and Brett D’Oliveria recovered the Worcestershire innings from 58 for four in the 10th over - when Daryl Mitchell, after reaching 33, was given out caught behind trying to cut Keogh - to 105 for four in the 14th.
But three wickets then went down for just six runs, including the very dangerous Ross Whiteley for just one caught at deep midwicket hy Wakely.
D’Oliveria was left with the lower-order to try and cobble together a competitive score.
He was dropped by Ben Sanderson diving forward at short third-man on 32 and went on to flat-bat Sanderson, now with ball in hand, down the ground and drove him past extra-cover before heaving a ball out of the ground over midwicket in the penultimate over of the innings.
He worked Kleinveldt through midwicket for a sixth boundary that brought him a third T20 fifty in 30 balls and helped add 47 runs from the final four overs of the innings.
But it was all to be in vain as Steelbacks claimed an emphatic victory.