Both goals came within 60 seconds.
On the hour mark Huddersfield levelled the tie thanks to a penalty kick given away by former Iron defender Jamie McCombe.
He tripped Andy Booth, with Danny Schofield converting the spot-kick.
In the closing minutes Huddersfield captain Rob Edwards sealed a Cardiff date by smashing the ball home after Booth got the ball caught under his feet.
Huddersfield will play Mansfield or Northampton, who play the second-leg of their semi-final at Field Mill tonight.
Mansfield have the advantage, having won the first leg 2-0 and having home advantage tonight.