Bell had been arguably Hatters' star man before his red card, sparking an improved second-half from the hosts after the Bluebirds dominated the opening period.
But with Town down to ten men for the final 18 minutes they were forced to defend and hang on for a point.
The result saw Mike Newell's men remain in 19th place in the Championship, while it mean the visitors continued their winless run which dated back to a 1-0 success against Burnley back at the start of November.
The Hatters made four changes to the side that drew 2-2 at leaders Birmingham on Friday night.
Fractured leg victim Markus Heikkinen and Lewis Emanuel, who injured a knee in the St Andrew's draw, were both missing as were Chris Coyne and Kevin Foley.
In came Russell Perrett, Bell, Ahmet Brkovic and Sol Davis, who took the captain's armband on his first senior start since suffering a stroke back in October.
Cardiff, without a win in nine games, made one change to the side that drew 0-0 with Crystal Palace as Alan Wright came in for Kevin McNaughton at left-back.
Town made a nervy start as Carlos Edwards, filling in at right-back gave the ball away twice in the opening stages, allowing the visitors to work an opening that saw Riccardo Scimeca fire just wide from 20 yards inside the first minute after Steve Thompson's shot was blocked.
Luton settled, but all they had to offer was a mis-hit, left-foot shot from Rowan Vine in the 12th minute that Neil Alexander held comfortably, after Edwards had helped Dean Morgan's half-cleared corner back into the penalty area.
It was the Bluebirds who began to dominate possession though and they worked two decent openings in the space of a minute.
Firstly Michael Chopra found space on the left and squared for Stephen McPhail to hit a 20-yard, left-foot shot that Dean Kiely dived to save in the 18th minute.
Seconds later, Willo Flood intercepted Leon Barnett's pass from defence and instantly found Chopra, who took a touch in the area before shooting tamely at Kiely from 14 yards when he perhaps could have done better.
Luton looked unable to get to grips with the game at all and Cardiff almost worked another opening in the 24th minute when Thompson brought down Kerrea Gilbert's cross and then saw his goalbound 18-yard shot blocked by Perrett.
As the Hatters struggled to get the ball out of their own half, Cardiff came again two minutes later as Scimeca played a one-two with Thompson before blazing high and wide from 15 yards.
Luton's plight was summed up as team-mates Morgan and Richard Langley came together in an angry confrontation and had to be pulled apart by referee Andy Penn.
Another Bluebirds attack on the half-hour cut Town open once again, as Gilbert found plenty of room on the right to cross for Thompson to head just wide from 14 yards.
Luton eventually woke from their slumber in the 32nd minute as Morgan robbed Gilbert and then raced on to Warren Feeney's measured pass before blasting just wide with his left-foot from a tight angle eight yards out.
The chance sparked another opening four minutes later as Morgan flicked on a long Kiely kick allowing Feeney to head on to Vine before getting on the end of his strike partner's cross only for his volleyed effort to hit Glenn Loovens and loop into the arms of Alexander.
Cardiff soon countered and after Thompson headed Chopra's half-blocked shot wide in the 37th minute, the same player then thundered a left-foot effort inches over from the edge of the area a minute later after good build-up play from Flood and Joe Ledley.
Luton ended the half on the offensive as Morgan took Davis' pass in stoppage time and unleashed a 25-yard right-foot effort that whistled just past Alexander's right-hand post.
Danger man Thompson planted another header just over for Cardiff three minutes into the second half before Feeney's 16-yard turn and shot was held by Alexander in the 50th minute after Bell and Edwards combined on the edge of the area.
Three minutes later there was bad news for Luton as Barnett picked up a fifth booking of the season handing him a forthcoming one-match suspension.
Worse was to follow ten minutes later as Langley became the second Town player in consecutive games to be stretchered off after a clash of heads in midfield.
The Hatters rallied though and three times came close to taking the lead in a hectic two minute spell.
Firstly Alexander pulled off a breathtaking double stop in the 66th minute to block Barnett's header from Brkovic's cross before pushing Vine's follow up over the bar.
From Morgan's resulting corner Alexander dived to his right to keep out Feeney's six-yard header and a minute later Alexander fell when coming for a deep cross allowing Brkovic to prod goalwards, only for Loovens to clear off the line.
Town's momentum was halted in the 72nd minute as the hosts were reduced to ten men when Bell received a second yellow card for a foul on Chopra and was given his marching orders.
The visitors tried to press home their numerical advantage and came close to sealing the points when Chopra latched on to Thompson's 78th minute flick-on and fired an angled 12-yard drive just past the far post.
Kiely then made a miraculous block four minutes time to preserve a point when the off-colour Edwards smacked a clearance that hit Flood and flew goalwards only for Luton's on-loan keeper to fling out an arm to divert the ball wide.