Keith Lowe scored his first goal for Kidderminster to help them to victory.
Lowe, signed from Wolves in August, headed home Martin Brittain's cross to set Harriers on their way to their 10th home win in the Conference this season.
Top scorer Justin Richards sealed the points when he converted Andy Ferrell's cross from 18 yards.
The Stags, triumphant just once on the road this season, created few chances, Matt Somner heading one of their rare threats over the crossbar.
Kidderminster manager Mark Yates told BBC Hereford and Worcester:
"It's a great record - 10 home league wins now - that's probably as many as we had last season.
"I'm delighted with them. I was disappointed on Saturday, obviously in the performance rather than the result, but they've got me back on side now.
"Bring on the next game because the boys are really confident."
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