Owls chief Stuart Gray felt his side had let a chance to continue their unbeaten away record in the league slip through their fingers.
“I thought if we had got our noses in front we would have won here as they would have been a bit nervous at home,” he said. “I thought once we went to 1-1 there was only one team that was going to win it, but it shows that if you do not defend your 18-yard box properly you are going to concede.
“We also got into some great areas but our final ball was poor.
“I had three strikers on at the end there and not one of them had a decent chance to score because the end product was very disappointing.”
Scott Young believes he and Danny Gabbidon can hold their heads high if this win proves their last game in temporary charge of the Bluebirds.
Manager-elect Russell Slade was among the crowd as goals from Sean Morrison, who also put through his own net for Wednesday’s equaliser, and Anthony Pilkington gave the Welsh club victory.
Morrison opened the scoring six minutes before the break, powerfully heading home from Peter Whittingham’s free-kick.
But Morrison then steered Chris Maguire’s cross into the bottom corner three minutes into the second half.
It did not prove costly as Pilkington also got off the mark in Cardiff colours, controlling Kenwyne Jones’s header and scoring past Keiren Westwood.
Cardiff City: Marshall, Brayford, Ecuele Manga, Sean Morrison, Da Silva (Ralls 85), Pilkington, Gunnarsson, Daehli, Whittingham, Noone (Ravel Morrison 62), Jones (Macheda 65). Unused substitutes: Le Fondre, Adeyemi, Moore, James.
Sheffield Wednesday: Westwood, Palmer, Buxton, Loovens, Mattock, Maguire (Hope 66), Semedo (Madine 75), Coke (Drenthe 66), Maghoma, Nuhiu, May. Unused substitutes: McCabe, Helan, Dielna, Kirkland.
Referee: M Bull (Essex).
Man of the match: Anthony Pilkington.