Middlesbrough had failed to score in four of their past five away Championship matches
Former Cardiff City boss Neil Warnock heaped more pressure on Bluebirds boss Mick McCarthy as the Welsh side were beaten for an eighth straight game.
Cardiff are now on their worst-ever run and have been beaten in their past six home games, also a new club record.
Middlesbrough took a deserved lead when Andraz Sporar scored from the penalty spot after Mark McGuinness' handball.
Martin Payero made the result safe with a smart 73rd-minute finish after Aden Flint hit the crossbar for Cardiff.
The Bluebirds did improve after half-time but there can be no denying they were second best in a game where their supporters again chanted against their own manager, with cries of "you're getting sacked in the morning" ringing out at Cardiff City Stadium.
The hosts headed into this contest on the back of seven defeats on the spin, their worst run since 1934 and a sparse crowd saw McCarthy make three changes to the side beaten at Fulham in midweek, with Wales striker Kieffer Moore dropped to the bench.
Popular former Bluebirds boss Warnock made two changes to his team as he returned to the Welsh capital for the first time since the return of fans, with both Warnock and former Cardiff captain, defender Sol Bamba, receiving a warm ovation.
Middlesbrough have been in better form than Cardiff and made a confident start, with both Paddy McNair and Payero firing wide and Sporar and Marcus Tavernier seeing efforts blocked.
The Bluebirds remarkably have failed to score a single first-half goal this season and never really looked like altering that unwanted statistic at the 14th time of asking as Warnock's side enjoyed much of the possession.
Mick McCarthy (left) succeeded Neil Harris as Cardiff boss in January 2021
Bamba came close to scoring against his former club, forcing Alex Smithies to save his header from a corner, before the visitors' pressure finally told on 35 minutes when Mark McGuinness handled Sporar's shot and the Slovenian slammed home the penalty.
Middlesbrough should have headed into half-time with a greater advantage, but Matt Crooks fired wide after going clean through with just Smithies to beat, while Smithies denied Uche Ikpeazu's near-post effort.
McCarthy replaced defender Perry Ng with Moore at the interval and the change of shape improved the hosts, who might have equalised on 53 minutes, only for striker James Collins to shoot straight at goalkeeper Joe Lumley.
Flint also went close for Cardiff when he clipped the crossbar with a header following Ryan Giles' dangerous cross, while Payero curled just wide at the other end as Cardiff committed players forward.
Paddy McNair fired against the crossbar as the visitors began to exert control again and they secured their first away win in five attempts against Cardiff when Payero took advantage of some ponderous defending and fired home.
The goal again prompted an angry response from Cardiff's fans, with the pressure on McCarthy only increasing with his side on their worst losing run in history and showing no signs of being able to halt their slide as only Smithies prevented a heavier defeat.
- Line-upsMatch StatsLive Text
Line-upsCardiff
Formation 4-2-3-1
25Smithies38Ng5Flint2McGuinness30Brown6Vaulks21Pack26Giles27Colwill29M Harris19Collins
- 25Smithies38NgSubstituted forMooreat 45'minutes5FlintBooked at 70mins2McGuinnessBooked at 34mins30Brown6VaulksSubstituted forKingat 79'minutes21PackBooked at 28mins26Giles27Colwill29M HarrisSubstituted forDaviesat 80'minutes19Collins
Substitutes
- 1Phillips4Morrison10Moore16Nelson32King36Evans39Davies
Middlesbrough
Formation 3-4-1-2
1Lumley17McNair22Bamba14Peltier16Howson7Tavernier25Crooks8Hernández10Payero9Ikpeazu11Sporar
- 1Lumley17McNair22Bamba14Peltier16Howson7Tavernier25Crooks8HernándezSubstituted forJonesat 63'minutes10Payero9IkpeazuBooked at 38minsSubstituted forCoburnat 85'minutes11SporarSubstituted forWatmoreat 82'minutes
Substitutes
- 13Olusanya18Watmore23Léa Siliki28Daniels30Kokolo35Jones37Coburn
Referee:Jeremy SimpsonAttendance:17,513Match StatsHome TeamCardiffAway TeamMiddlesbroughPossessionHome52%Away48%ShotsHome9Away21Shots on TargetHome1Away6CornersHome4Away14FoulsHome14Away11Live TextPost update
Match ends, Cardiff City 0, Middlesbrough 2.
90'+3'Full Time
Second Half ends, Cardiff City 0, Middlesbrough 2.
90'Post update
Isaiah Jones (Middlesbrough) wins a free kick on the left wing.
90'Post update
Foul by Mark McGuinness (Cardiff City).
89'Post update
Attempt missed. Duncan Watmore (Middlesbrough) right footed shot from the centre of the box is close, but misses to the left. Assisted by Marcus Tavernier with a through ball following a fast break.
87'Post update
Corner, Middlesbrough. Conceded by Eli King.
86'Post update
Corner, Middlesbrough. Conceded by James Collins.
86'Post update
Attempt saved. Josh Coburn (Middlesbrough) left footed shot from a difficult angle on the right is saved in the bottom right corner. Assisted by Duncan Watmore.
86'Post update
Marlon Pack (Cardiff City) wins a free kick in the defensive half.
86'Post update
Foul by Marcus Tavernier (Middlesbrough).
85'Substitution
Substitution, Middlesbrough. Josh Coburn replaces Uche Ikpeazu.
82'Substitution
Substitution, Middlesbrough. Duncan Watmore replaces Andraz Sporar.
81'Post update
Ciaron Brown (Cardiff City) wins a free kick in the defensive half.
81'Post update
Foul by Uche Ikpeazu (Middlesbrough).
80'Post update
Attempt saved. Uche Ikpeazu (Middlesbrough) left footed shot from outside the box is saved in the top left corner.
80'Substitution
Substitution, Cardiff City. Isaak Davies replaces Mark Harris.
79'Substitution
Substitution, Cardiff City. Eli King replaces Will Vaulks.
78'Post update
Kieffer Moore (Cardiff City) wins a free kick on the left wing.
78'Post update
Foul by Matt Crooks (Middlesbrough).
75'Post update
Hand ball by Uche Ikpeazu (Middlesbrough).
Page 1 of 6rewindpreviousNavigate to the next pagenextNavigate to the last pageforward
Source: bbc.com