Harriers were stung by a late Wrexham goal as Elliott Durell’s deflected 84th-minute strike gave the hosts all three points.
It was a cruel blow for Gary Whild’s side as a game of few clear-cut chances looked to be heading for a goalless draw.
As the Dragons pushed forward with six minutes of normal time remaining, they retained possession in the penalty area and Harriers were unable to clear the threat.
Neil Ashton’s cross was held up well by Andy Bishop who, with his back to goal, found Durrell - whose shot took a whack on its way into the back of the net.
The defeat pushes Harriers down to ninth in the Vanarama Conference, while Wrexham move into third.
Both sides were unchanged from their respective weekend victories against Woking and Eastleigh, although Dragons boss Kevin Wilkin switched Steve Tomassen with Theo Bailey-Jones on the bench.
An uneventful first half saw few clear-cut chances for either side, as it remained relatively even throughout.
Kidderminster’s best chance came after 34 minutes, when good play between Kevin Nicholson and Aman Verma allowed Marvin Johnson
to sweep along the left and drill a low cross past the goalmouth.
With Michael Gash on the other side of the penalty area, all Johnson’s ball needed was a man on the far post to tap home.
Wrexham were first to dip their toes in the water as close-range efforts by Connor Jennings and Mark Carrington were blocked and caught respectively inside the first 10 minutes.
Harriers’ back line were in top form, with Chey Dunkley
demonstrating some good skill as he turned effortlessly to keep possession from Jennings, while Kyle Storer made a perfectly-timed tackle to dispossess Durrell inside his own box.
Reece Styche and Jack Byrne both saw shots roll wide, while Gash couldn’t make a strong connection with Nicholson’s cross and sent a swerving header over the bar.
Amidst loud boos after the home faithful took exception to his involvement in a Harriers free-kick, Johnson stepped up the pace in the second half and crafted various attacking moves down the left.
And in similar situations to his first-half attempt at an assist, Josh Gowling
and Dunkley both saw crosses flash across the penalty area without a team-mate able to stick the ball into the back of the net.
Meanwhile, Gash worked tirelessly up front, threatening both in the air and forcing Wrexham ‘keeper Dan Bachmann into a firm stop.
Bachmann also had to be alert to deny a strong Storer shot before Johnson sent a strike inches wide in the dying stages.
The hosts’ best effort fell to Louis Moult, who blazed carelessly over an unguarded net after Danny Lewis
failed to claim a catch under pressure from Jennings, but Durrell struck late on to send Harriers home empty-handed.