The result opens a five-point gap between fifth-placed Leicester and their opponents who have now lost their last five away games.
Leicester started brightly with Lloyd Dyer's long ball letting in Waghorn for a run on goal but Kevin McNaughton got back to snuff out the danger.
Anthony Gerrard then cut out Bruno Berner's dangerous cross before Adam Matthews cleared a Jack Hobbs header off the line.
At the other end Hobbs blocked Ross McCormack's 12-yard drive before Peter Whittingham flashed a shot just wide.
But it was Leicester who continued to press and they had a penalty appeal waved aside when Michael Morrison's shot appeared to strike McNaughton's arm.
But Leicester's persistence paid dividends on 29 minutes when Andy King's header from Berner's cross found Waghorn who reacted sharply to squeeze home an angled shot from six yards.
Cardiff, far more robust than in the lame midweek loss at Ipswich, almost levelled just before the break when Mark Kennedy drove narrowly wide.
And after the restart Chris Burke looked menacing as he bore down on goal but disappointingly shot weakly at the keeper.
James Vaughan was thrown into the action on 63 minutes, just 48 hours after arriving at the Walkers Stadium on loan from Everton.
But it was former Blackburn star Paul Gallagher who next caught the eye for the Foxes with a 35-yard thunderbolt which was a whisker away from doubling his side's lead.
Cardiff continued to threaten with McCormack seeing a fierce drive beaten away by Weale and then weighing in with another shot which flew just over.
Weale kept the home side's lead intact ten minutes from the end when he dived at his near post to smother Jay Bothroyd's shot on the turn.
Leicester were denied what seemed a legitimate penalty late on when Anthony Gerrard hauled down Vaughan inside the 18-yard area and, right at the death, Stephen McPhail had a half-chance to level for the visitors but hooked a 16-yard shot over the bar.