Matthew Connolly's first-half goal sent Cardiff into second place in the Championship and gave them a record-equalling ninth successive home win.
Their 1-0 victory saw them leapfrog Middlesbrough and hand the visitors their first defeat in nine games.
Peter Whittingham's 19th minute cross found an unmarked Connolly near the far post to head home.
Boro skipper Grant Leadbitter's late drive almost levelled, but his shot went agonisingly wide.
Recalled because of an injury to full-back Kevin McNaughton, Connolly's fourth goal of the season - aided by skipper Mark Hudson, whose run distracted the Middlesbrough defence - settled an encounter bedevilled by five substitutions due to injuries.
His goal came after the hosts' first casualty, Ben Turner, limped off to be replaced by 18-year-old Ben Nugent, who came on for his league debut.
Leadbitter then spotted David Marshall off his line but the Cardiff goalkeeper was equal to the Middlesbrough captain's effort, tipping his shot over the bar.
After substitute Joe Ralls brought Emanuel Ledesma down, the Argentine's powerful shot beat Marshall but cannoned off the crossbar.
Scott MacDonald then squandered a fine chance after being released by Ledesma's clever chip, lifting the ball over the bar as Marshall charged out to narrow the angle.
After the break Whittingham's clever low free-kick brought a good save out of Boro keeper Jason Steele.
At the other end the introduction of Marvin Emnes gave the visitors some impetus.
But Bellamy's entry to the fray on the hour mark was equally effective for the home side, and the Bluebirds survived Boro's late attempts to level.
Cardiff manager Malky Mackay:
"I'm delighted with the character of the team and the fact we kept another clean sheet at home. But that is no surprise to me because I see that from the players every day.
"Middlesbrough had been on a roll and we knew it would be a tough game. But it became tougher when we lost two players after 20 minutes.
"We had to put young players in and they did brilliantly well.To show that resilience against a good team showed the commitment to the cause and there are no egos at this club."
Middlesbrough manager Tony Mowbray:
"I thought we played pretty well. There is a long way to go in the rest of the season and if we perform like we did today for long spells then we will be okay.
"Cardiff are a resilient side who defended well and put their bodies on the line. They had to do that. But they got their noses in front. With Peter Whittingham's left foot, they are dangerous from set-plays and they scored from one.
"But the longer the game went on the chances came and went for us and, ultimately, we didn't manage to stick one in the back of the net. I picked a team to win the game."
- 01 Marshall
- 03 Taylor (Ralls - 26' )
- 05 Hudson
- 06 Turner (Nugent - 14' )
- 12 Connolly
- 07 Whittingham Booked
- 13 Kim Bo-Kyung
- 16 Noone
- 17 Gunnarsson (Bellamy - 61' )
- 20 Mason
- 22 Helguson
- 32 Lewis
- 31 Nugent
- 11 Conway
- 21 Ralls
- 25 Frei
- 15 Gestede
- 39 Bellamy
- 01 Steele
- 02 Hoyte
- 03 Bikey
- 04 Friend (Bailey - 71' )
- 15 Hines Booked
- 07 Leadbitter Booked
- 16 McEachran
- 38 Haroun (Smallwood - 30' )
- 11 Ledesma
- 17 Jutkiewicz (Emnes - 60' )
- 27 McDonald
- 32 Leutwiler
- 08 Thomson
- 10 Bailey
- 33 Smallwood
- 09 Emnes
- 22 Williams
- 30 Miller
Live Text Commentary
Full Time The referee ends the match.90:00 +2:57
Heidar Helguson has a headed effort at goal from close range which goes wide of the left-hand upright.90:00 +0:48
Grant Leadbitter has an effort at goal from outside the area which goes wide left of the target.88:59
Heidar Helguson concedes a free kick for a foul on Richard Smallwood. Grant Leadbitter takes the free kick.87:45
Grant Leadbitter challenges Heidar Helguson unfairly and gives away a free kick. David Marshall restarts play with the free kick.85:17
The offside flag is raised against Justin Hoyte. David Marshall takes the indirect free kick.84:03
Inswinging corner taken right-footed by Craig Bellamy from the left by-line to the near post, Justin Hoyte makes a clearance.81:44
Justin Hoyte takes a shot. Blocked by Mark Hudson.81:01
Unfair challenge on Josh McEachran by Craig Bellamy results in a free kick. Josh McEachran restarts play with the free kick.79:56
Richard Smallwood gives away a free kick for an unfair challenge on Heidar Helguson. Peter Whittingham restarts play with the free kick.79:15
Corner taken by Grant Leadbitter played to the near post, Matthew Connolly manages to make a clearance.77:37
Free kick awarded for an unfair challenge on Andre Bikey by Craig Bellamy. Grant Leadbitter restarts play with the free kick.76:05
Corner from the left by-line taken by Grant Leadbitter, free kick awarded for an unfair challenge on David Marshall by Scott McDonald. Indirect free kick taken by David Marshall.75:28
Marvin Emnes takes a shot. Save by David Marshall. Inswinging corner taken by Emmanuel Ledesma from the right by-line, clearance by Ben Nugent.73:56
Marvin Emnes has a header from close range and clears the crossbar.70:57 Substitution
Substitution Nicky Bailey replaces George Friend.67:27
Scott McDonald has an effort at goal from just outside the box which goes wide of the right-hand post.66:10
Scott McDonald takes a shot. Blocked by Mark Hudson.65:48
Emmanuel Ledesma takes a shot.63:29
Grant Leadbitter takes a shot. Save by David Marshall.
Unfair challenge on Andre Bikey by Craig Noone results in a free kick. Jason Steele restarts play with the free kick.60:30 Substitution
Substitution Craig Bellamy on for Aron Gunnarsson.59:07 Substitution
Substitution Marvin Emnes on for Lukas Jutkiewicz.58:50
Shot from deep inside the area by Lukas Jutkiewicz clears the crossbar.56:53
Free kick awarded for an unfair challenge on Andre Bikey by Joe Mason. Indirect free kick taken by Jason Steele.56:25
Unfair challenge on Grant Leadbitter by Joe Mason results in a free kick. Grant Leadbitter restarts play with the free kick.55:23
Peter Whittingham crosses the ball from the free kick left-footed from right channel, save by Jason Steele.55:23 Booking
Booking The referee shows Grant Leadbitter a yellow card.55:02
Craig Noone fouled by Grant Leadbitter, the ref awards a free kick.54:24
Indirect free kick taken by Emmanuel Ledesma.54:24 Booking
Booking Peter Whittingham booked.54:16
Peter Whittingham concedes a free kick for a foul on Emmanuel Ledesma.53:20
Scott McDonald is ruled offside. David Marshall takes the indirect free kick.50:32
Headed effort from inside the area by Scott McDonald misses to the left of the target.48:54
Inswinging corner taken left-footed by Emmanuel Ledesma from the right by-line, free kick awarded for an unfair challenge on Mark Hudson by Scott McDonald. Indirect free kick taken by David Marshall.47:54
Corner taken right-footed by Grant Leadbitter, save by David Marshall.45:13
Scott McDonald takes a shot. Save by David Marshall.45:01
The referee starts the second half.45:00 +5:47 Half time
Half Time The referee blows for half time.45:00 +4:12
Free kick awarded for an unfair challenge on Craig Noone by Richard Smallwood. David Marshall takes the indirect free kick.45:00 +1:45
Scott McDonald produces a left-footed shot from close in that goes over the bar.44:44
Heidar Helguson takes a shot. Blocked by Andre Bikey. Free kick awarded for an unfair challenge on Scott McDonald by Matthew Connolly. Andre Bikey restarts play with the free kick.42:06
Grant Leadbitter takes a shot. Blocked by Craig Noone.38:21
Shot from just outside the penalty area by Grant Leadbitter misses to the left of the target.37:10
The offside flag is raised against Joe Mason. Free kick taken by Jason Steele.36:33
The ball is swung over by Craig Noone, save by Jason Steele.35:31
Foul by George Friend on Craig Noone, free kick awarded. Craig Noone takes the indirect free kick.34:03
Aron Gunnarsson challenges Emmanuel Ledesma unfairly and gives away a free kick. Jason Steele takes the indirect free kick.30:03
Unfair challenge on Emmanuel Ledesma by Joe Ralls results in a free kick. Emmanuel Ledesma shoots direct from the free kick,29:21 Substitution
Substitution Richard Smallwood on for Faris Haroun.27:12
Emmanuel Ledesma takes the inswinging corner, clearance by Heidar Helguson.26:22
Grant Leadbitter takes a shot. David Marshall makes a save. Emmanuel Ledesma takes a inswinging corner from the right by-line played to the near post, clearance by Ben Nugent.24:29 Substitution
Substitution Joe Ralls on for Andrew Taylor.24:29
The referee blows for offside. David Marshall takes the indirect free kick.23:14
Emmanuel Ledesma takes a shot. Blocked by Mark Hudson.22:42
Mark Hudson has an effort at goal from outside the penalty box which goes wide right of the target.20:21
Ben Nugent concedes a free kick for a foul on Scott McDonald. Free kick taken by Jason Steele.19:48
Outswinging corner taken from the left by-line by Peter Whittingham, clearance by Faris Haroun.18:18
The assist for the goal came from Peter Whittingham.18:18 Goal scored
Goal! - Matthew Connolly - Cardiff 1 - 0 Middlesbro Matthew Connolly grabs a headed goal from inside the six-yard box. Cardiff 1-0 Middlesbrough.17:44
Inswinging corner taken from the right by-line by Peter Whittingham,17:17
Emmanuel Ledesma takes a shot. Blocked by Ben Nugent.15:41
The assistant referee flags for offside against Heidar Helguson. Indirect free kick taken by Jason Steele.13:46 Substitution
Substitution Ben Turner goes off and Ben Nugent comes on.12:41
Emmanuel Ledesma takes a shot. Blocked by Mark Hudson.4:20
Shot from just outside the box by Bo-Kyung Kim goes over the bar.3:11
Peter Whittingham shoots direct from the free kick, blocked by Emmanuel Ledesma.3:11 Booking
Booking Seb Hines is shown a yellow card.2:50
Free kick awarded for an unfair challenge on Craig Noone by Seb Hines.0:31
Free kick awarded for a foul by Aron Gunnarsson on Scott McDonald. Emmanuel Ledesma restarts play with the free kick.0:00
The match gets underway.
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