Having earlier collected a fifth booking of the season to rule himself out of City's next game against Peterborough, captain Mark Hudson headed the visitors into a 30th-minute lead.
Following Jason Lowe's yellow-card challenge on Craig Bellamy in the 29th minute and an associated bout of handbags, Peter Whittingham punted the resulting free-kick hopefully forward, but Rovers could only clear as far as Craig Noone and his left-footed delivery from the right was planted past Paul Robinson by Hudson.
Bellamy, who counts Rovers among his vast collection of former clubs, struck the crossbar towards the end of a first half where Blackburn produced a woeful 45 minutes - a worryingly familiar theme of their recent outings.
One of Rovers' few bright sparks, on-loan Manchester United forward Josh King, brought them level in the 51st minute.
Substitute Colin Kazim-Richards controlled a Jordan Rhodes' flick on and released King to slot under onrushing Cardiff goalkeeper David Marshall.
However, Bellamy restored Cardiff's advantage four minutes later after exchanging headers with Heidar Helguson as the hosts failed to deal with another long, hopeful free-kick.
Substitutes Joe Mason and Kim Bo-Kyung then completed Blackburn's misery with two quick goals.
The former made the points safe six minutes from time by slotting home from Helguson's flick on before the striker grabbed another assist by teeing up Kim to sweep home.
Rovers boss Henning Berg was left to survey a fourth defeat from eight games in charge that leaves his side 15 points behind the leaders after 21 games and, perhaps more significantly, four shy of the play-off places ahead of the weekend fixtures.
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- Craig Bellamy