David Winters' inspired second-half double sent Ross County through to a fourth round showdown with Clyde.
The former Dundee United striker's recent rush of goals continued with a sixth and seventh from five games to dismiss the Diamonds.
A sudden County offensive brought the opener from the penalty spot after 23 minutes.
Former Aberdeen midfielder Fergus Tiernan slipped Alexander Burke through into the box and the ex-Killie striker was blatantly tripped by David Dunn.
Burke kept a cool head to send a lofted penalty over the body of diving Mark McGeown.
County deserved their second after 32 minutes on pressure, but there was a fair element of good fortune.
Keeper McGeown went to punch John Rankin's free-kick from deep under pressure from Martin Canning, but simply helped the ball onward into the net.
Airdrie pulled one back after 40 minutes, with County caught ball-watching.
Mark Roberts sent the ball in from the right, Owen Coyle headed on and Martin Hardie's acrobatic first-time wallop beat Colin Stewart from six yards.
County stretched their lead in some style after 51 minutes. John Robertson's cross from the right found Winters executing a fine header six yards out.
Just four minutes later, Winters was sent waltzing clean through on the keeper by a long Rankin ball to calmly roll home the fourth.