First-half goals from central defender Gary Breen and veteran striker Marcus Stewart had put the Black Cats into a commanding lead, but when defender Tony Vidmar completely deceived goalkeeper Thomas Myhre with five minutes left, the mood of a bumper crowd suddenly changed.
In a dramatic finish Cardiff substitute Alan Lee was sent off for elbowing Stephen Caldwell but still the visitors surged forward for an unexpected equaliser only for the home side to hold out for a second home win of the week.
Dean Whitehead fired just past the post before Sunderland surged into a fourth minute lead.
Cardiff skipper Graham Kavanagh collided with team-mate Rhys Weston which allowed Andy Welsh, deputising for the injured Julio Arca, to centre deep where Breen dilled a low shot which was helped into the net by goalkeeper Neil Alexander.
Cardiff responded with Cameron Jerome having a shot blocked, Junichi Inamoto firing just past the post and Kavanagh blasting a free-kick narrowly wide.
Sunderland lost full-back Mark Lynch, making a rare appearance for the suspended Stephen Wright, with a dislocated knee cap but the home side surged further ahead in the 42nd minute when Stewart headed home his 13th goal of the season from Whitehead's centre.
The game should have been put beyond the visitors in the 53rd minute when Stewart and substitute Liam Lawrence up the easiest of chances for Welsh who completely missed his kick with the goal at his mercy.
The best chances of the second half fell to Cardiff with Jobi McAnuff and Inamoto guilty of squandering excellent opportunities when well placed.
Vidmar raised hopes when a cross-cum-centre sailed over a hapless Mhyre and a powerfully struck free-kick from Daniel Gabbidon flew just past the post to the relief of the Sunderland fans.