Neither side produced much in the first hour but both were gifted goals by mistakes, before Town stepped up the pace late on to clinch the points.
In a shocking first half, debutant goalkeeper Tony Warner blocked an angled Darren Bent shot with his knees before allowing a shot by the same player to beat him on his near post after 21 minutes.
Ipswich carried little threat, but visitors Cardiff were even worse, their only efforts of the first period being high and wide from both Alan Lee and Richard Langley, while at the other end a Dean Bowditch volley looped over Warner but dropped narrowly wide.
Town almost doubled their lead immediately after the break when an in-swinging corner from Kevin Horlock was flicked goalwards by Jason De Vos, and Warner did well to parry it away.
It looked as if only a home mistake would let Cardiff back in, and so it proved when Lee pounced on Richard Naylor's mis-hit back pass to take the ball on and fire past Kelvin Davis.
Bowditch curled a shot wide before Town regained the lead in the 67th minute.
A slick passing move ended with substitute Pablo Counago feeding Bowditch on the right, and he picked out the on-rushing Tommy Miller who drove the ball beyond Warner.
Town should have sealed the points after 81 minutes when Counago put Bent clear. The striker rounded Warner but was left with a tight angle and chose to slip the ball back to Counago, who blazed over from eight yards.
Counago was also denied a goal from a clever chip, which Warner palmed backwards but pushed away from near the line, before Town sealed it three minutes from time.
Bent broke away down the right flank and pulled it back to Ian Westlake, who scuffed his shot, but it was enough to beat the wrong-footed Warner and go in off the post.