The win moved Cardiff three points clear at the top of the table.
Leicester laid siege to the Bluebirds' goal in the first half with chance after chance going begging. David Marshall made a handful of saves to keep the Foxes at bay and, when he was beaten by Andy King's long-range effort, a post came to his rescue.
Craig Bellamy looked a threat on the counter-attack throughout and it was he who grabbed the only goal of the game against the run of play after 25 minutes. The Wales international showed great technique after collecting Craig Conway's pass to find the bottom left-hand corner of the net from 12 yards out.
That seemed to knock the stuffing out of Leicester, who created very little afterward.
Leicester started brightly with Danny Drinkwater firing over early on.
David Nugent became the first home player of the afternoon to be frustrated by Marshall when the Scot parried his effort from the edge of the area.
King struck a post after 13 minutes when the ball broke to him outside the area after Marshall had kept out Wes Morgan's header.
Marshall then twice denied Anthony Knockaert when the Frenchman let fly from long range before Bellamy delivered the killer blow for the Foxes.
Jamie Vardy might have done better than head over the crossbar before half-time in what turned out to be Leicester's final real chance.
Pearson's side tried to push for an equalising goal in the second half, but were always wary of the threat caused by Bellamy's pace, perhaps preventing them from committing as many players forward as they would have liked.
Nugent and substitute Ben Marshall fired in shots from outside the box but never worried the Cardiff keeper.
Back-to-back defeats are a blow to Leicester's automatic promotion aspirations, which will come under intense scrutiny again on Boxing Day when they travel to Pearson's former club Hull.
The victory gives Cardiff a slight cushion ahead of their home game against title rivals Crystal Palace in four day's time.