Jordan Rhodes' first goal for Town gave Jim Magilton's side a share of the points after Gavin Rae had given the visitors a first-half lead.
Rae tapped in seven minutes before the break after great work by Aaron Ramsey and Cardiff threatened a second before Rhodes struck on 73 minutes.
Town bombarded the Bluebirds over the closing stages and Danny Haynes had the ball in the net in the 90th minute but referee Russell Booth stopped the celebrations with a blast of his whistle for a free-kick to the away side.
Town made two changes to the side that lost at Colchester at the weekend, Gavin Williams and Velice Sumuloikoski making way for Tommy Miller and Gary Roberts.
Haynes' pace caused Wembley bound Cardiff problems in the early minutes, his cross found Alan Lee but the striker failed to control the ball inside the box.
At the other end Tony Capaldi had a piledriver blocked by a brave challenge from Jason De Vos.
Miller then sent Haynes clear down the left but his cross evaded all, then Owen Garvan's exellent pass almost released Lee.
More good work by Haynes then set up Roberts, whose cross was returned to Haynes, his shot blocked by Roger Johnson
De Vos sent a header into the sidenetting from Alan Quinn's cross as Town looked the more likely to open the scoring, Haynes involved again in a link up with Roberts, the Blues' striker denied again by Darcy Blake's challenge.
Garvan was booked for a trip on Rae as Cardiff threatened, Ramsey's free-kick going just wide.
On 28 minutes Town missed a gilt edged chance to go in front, Lee bursting clear on goal but dragging his shot wide of the far post from an angle.
Sito followed Garvan into referee Russell Booth's book just past the half hour and on 37 minutes the visitors went ahead, the highly rated Ramsey weaving his way into the box and crossing perfectly for Rae to tap in at the far post.
The Bluebirds had an escape seconds later when 'keeper Peter Enckleman dropped a free-kick but Lee and Haynes couldn't pounce.
Rhodes replaced Roberts at the break and the teenager twice threatened to get in on goal in the first few minutes.
Riccardo Scimeca volleyed over with an ambitious effort from 25 yards as Cardiff responded.
Bruce then brilliantly denied Ramsey with a block inside the Town box as the visitors countered with men over, Quinn blocked out at the other end by Johnson's resolute defending.
Rae tried his luck from distance as Cardiff threatened a second on the break. Capaldi yellow carded for a foul on Haynes.
David Wright replaced Sito just past the hour, Peter Whittingham coming on for Capaldi in Cardiff's first change, Trevor Sinclair coming on for Scimeca soon after.
With Town pushing forward, the Bluebirds continued to look dangerous on the break, Ramsey having a shot blocked by Danny Simpson inside the Town area.
The equaliser came on 73 minutes with Rhodes taking advantage of the static away defence as they looked for the offside flag, the teenager calmly sliding the ball past Enckelman.
The goal lifted Blues, Bruce bravely winning a header inside the box but Enckelman smothered the danger.
Sumulikoski replaced Quinn for the last 12 minutes, Garvan's trickery creating an opening for himself on the edge of the box but his shot went just wide.
Jimmy Floyd Hasselbaink came on for Joe Ledley in Cardiff's final change as both teams looked for a winner, Haynes' cross almost falling for Rhodes six yards out.
Garvan tested Enckelman from 20 yards with a right foot drive after De Vos had headed on then Haynes fired into the roof of the net with a brilliant strike but referee Booth gave a free-kick to the visitors for a push in the goalmouth melee that proceeded the ball falling to Haynes.
Garvan, Rhodes and Miller both went close in added on time but Town couldn't find a winner. The draw extends Blues' record to one defeat in 25 League games at Portman Road and lifts the Club into seventh with Norwich the visitors on Sunday.
Town: Bywater, Simpson, De Vos, Bruce, Sito (Wright 62), Quinn (Sumulikoski 78), Garvan, Miller, Roberts (Rhodes 46), Lee, Haynes. Subs not used: Colgan, Williams. Booked: Garvan, Sito.
Cardiff: Enckleman, Blake, Loovens, Johnson, Capaldi (Whittingham 62), Ramsey, Rae, Scimeca (Sinclair 69), Ledley (Hasselbaink 82), McPhail, Thompson. Subs not used: Purse, Oakes. Booked: Capaldi.
Att: 20,311
