Kidderminster leapfrogged Tamworth in the Blue Square Bet Premier table with victory at Aggborough.
Lee Vaughan opened the scoring with his sixth-minute penalty after Marc Williams was fouled by Tamworth defender Francino Francis.
Striker Steve Guinan doubled the lead 12 minutes later, finding the top corner from 20 yards out.
Substitute Liam McDonald came closest to a consolation for the visitors with a 73rd-minute effort that flew wide.
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Kidderminster assistant manager Gary Whild told BBC Hereford and Worcester:
"It was good to win but I don't think it will take away the total disappointment, because we know how much the FA Cup means to everybody.
"It meant a lot to us and, in the time that we have been here, we haven't had that many lows but unfortunately that [defeat at Corby Town] was disappointing.
"But we have moved on and it was a perfect response and I thought that was a well-deserved win."